Common Weakness Enumeration
CWE-367
AllowedTime-of-check Time-of-use (TOCTOU) Race Condition
Abstraction: Base · Status: Incomplete
The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.
1067 vulnerabilities reference this CWE, most recent first.
GHSA-78GX-8V3C-JQWC
Vulnerability from github – Published: 2026-07-09 18:31 – Updated: 2026-07-09 18:31
VLAI
Details
varstored is a component of the Xapi toolstack handling UEFI Variables for a VM. It has a communication path with OVMF inside the VM involving mapping a buffer prepared by OVMF.
Within varstored, there were insufficient compiler barriers, creating TOCTOU issues with data in the shared buffer.
The exact vulnerable behaviour depends on the code generated by the compiler. In a build of varstored using default settings, the attacker can control an index used in a jump table.
Severity
{
"affected": [],
"aliases": [
"CVE-2025-58151"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-09T16:16:33Z",
"severity": "CRITICAL"
},
"details": "varstored is a component of the Xapi toolstack handling UEFI Variables\nfor a VM. It has a communication path with OVMF inside the VM involving\nmapping a buffer prepared by OVMF.\n\nWithin varstored, there were insufficient compiler barriers, creating\nTOCTOU issues with data in the shared buffer.\n\nThe exact vulnerable behaviour depends on the code generated by the\ncompiler. In a build of varstored using default settings, the attacker\ncan control an index used in a jump table.",
"id": "GHSA-78gx-8v3c-jqwc",
"modified": "2026-07-09T18:31:50Z",
"published": "2026-07-09T18:31:50Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-58151"
},
{
"type": "WEB",
"url": "https://xenbits.xen.org/xsa/advisory-478.html"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2026/01/27/2"
},
{
"type": "WEB",
"url": "http://xenbits.xen.org/xsa/advisory-478.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-7CR4-QX2C-73WM
Vulnerability from github – Published: 2023-06-12 21:30 – Updated: 2024-04-04 04:44
VLAI
Details
Potential Time-of-Check to Time-of Use (TOCTOU) vulnerabilities have been identified in the HP BIOS for certain HP PC products which may allow arbitrary code execution, denial of service, and information disclosure.
Severity
7.8 (High)
{
"affected": [],
"aliases": [
"CVE-2022-43777"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-06-12T20:15:10Z",
"severity": "HIGH"
},
"details": "Potential Time-of-Check to Time-of Use (TOCTOU) vulnerabilities have been identified in the HP BIOS for certain HP PC products which may allow arbitrary code execution, denial of service, and information disclosure.",
"id": "GHSA-7cr4-qx2c-73wm",
"modified": "2024-04-04T04:44:06Z",
"published": "2023-06-12T21:30:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-43777"
},
{
"type": "WEB",
"url": "https://support.hp.com/us-en/document/ish_7709808-7709835-16/hpsbhf03835"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-7F5Q-X8VX-PFRP
Vulnerability from github – Published: 2023-09-13 18:31 – Updated: 2024-04-04 07:39
VLAI
Details
A flaw was found in KVM AMD Secure Encrypted Virtualization (SEV) in the Linux kernel. A KVM guest using SEV-ES or SEV-SNP with multiple vCPUs can trigger a double fetch race condition vulnerability and invoke the VMGEXIT handler recursively. If an attacker manages to call the handler multiple times, they can trigger a stack overflow and cause a denial of service or potentially guest-to-host escape in kernel configurations without stack guard pages (CONFIG_VMAP_STACK).
Severity
5.3 (Medium)
{
"affected": [],
"aliases": [
"CVE-2023-4155"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-09-13T17:15:10Z",
"severity": "MODERATE"
},
"details": "A flaw was found in KVM AMD Secure Encrypted Virtualization (SEV) in the Linux kernel. A KVM guest using SEV-ES or SEV-SNP with multiple vCPUs can trigger a double fetch race condition vulnerability and invoke the `VMGEXIT` handler recursively. If an attacker manages to call the handler multiple times, they can trigger a stack overflow and cause a denial of service or potentially guest-to-host escape in kernel configurations without stack guard pages (`CONFIG_VMAP_STACK`).",
"id": "GHSA-7f5q-x8vx-pfrp",
"modified": "2024-04-04T07:39:29Z",
"published": "2023-09-13T18:31:26Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-4155"
},
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/CVE-2023-4155"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2213802"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-7G9H-H4FM-JQ9P
Vulnerability from github – Published: 2024-03-14 18:30 – Updated: 2024-03-14 18:30
VLAI
Details
Race condition in BIOS firmware for some Intel(R) Processors may allow a privileged user to potentially enable escalation of privilege via local access.
Severity
7.2 (High)
{
"affected": [],
"aliases": [
"CVE-2023-32282"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-03-14T17:15:50Z",
"severity": "HIGH"
},
"details": "Race condition in BIOS firmware for some Intel(R) Processors may allow a privileged user to potentially enable escalation of privilege via local access.",
"id": "GHSA-7g9h-h4fm-jq9p",
"modified": "2024-03-14T18:30:30Z",
"published": "2024-03-14T18:30:30Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-32282"
},
{
"type": "WEB",
"url": "https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00929.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:N/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-7JMR-43QJ-PW47
Vulnerability from github – Published: 2025-02-11 18:31 – Updated: 2025-02-28 02:45
VLAI
Summary
Magento Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability
Details
Adobe Commerce versions 2.4.7-beta1, 2.4.7-p3, 2.4.6-p8, 2.4.5-p10, 2.4.4-p11 and earlier are affected by a Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability that could result in a security feature bypass. An attacker could exploit this race condition to alter a condition after it has been checked but before it is used, potentially bypassing security mechanisms. Exploitation of this issue requires user interaction.
Severity
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "magento/community-edition"
},
"ranges": [
{
"events": [
{
"introduced": "2.4.7-beta1"
},
{
"fixed": "2.4.7-p4"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Packagist",
"name": "magento/community-edition"
},
"ranges": [
{
"events": [
{
"introduced": "2.4.6-p1"
},
{
"fixed": "2.4.6-p9"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Packagist",
"name": "magento/community-edition"
},
"ranges": [
{
"events": [
{
"introduced": "2.4.5-p1"
},
{
"fixed": "2.4.5-p11"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Packagist",
"name": "magento/community-edition"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.4.4-p12"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Packagist",
"name": "magento/community-edition"
},
"versions": [
"2.4.7"
]
},
{
"package": {
"ecosystem": "Packagist",
"name": "magento/community-edition"
},
"versions": [
"2.4.6"
]
},
{
"package": {
"ecosystem": "Packagist",
"name": "magento/community-edition"
},
"versions": [
"2.4.5"
]
},
{
"package": {
"ecosystem": "Packagist",
"name": "magento/community-edition"
},
"versions": [
"2.4.4"
]
},
{
"package": {
"ecosystem": "Packagist",
"name": "magento/community-edition"
},
"versions": [
"2.4.8-beta1"
]
},
{
"package": {
"ecosystem": "Packagist",
"name": "magento/project-community-edition"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "2.0.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2025-24432"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": true,
"github_reviewed_at": "2025-02-28T02:45:01Z",
"nvd_published_at": "2025-02-11T18:15:45Z",
"severity": "LOW"
},
"details": "Adobe Commerce versions 2.4.7-beta1, 2.4.7-p3, 2.4.6-p8, 2.4.5-p10, 2.4.4-p11 and earlier are affected by a Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability that could result in a security feature bypass. An attacker could exploit this race condition to alter a condition after it has been checked but before it is used, potentially bypassing security mechanisms. Exploitation of this issue requires user interaction.",
"id": "GHSA-7jmr-43qj-pw47",
"modified": "2025-02-28T02:45:02Z",
"published": "2025-02-11T18:31:42Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-24432"
},
{
"type": "PACKAGE",
"url": "https://github.com/magento/magento2"
},
{
"type": "WEB",
"url": "https://helpx.adobe.com/security/products/magento/apsb25-08.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Magento Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability"
}
GHSA-7MP4-25J8-HP5Q
Vulnerability from github – Published: 2026-03-11 00:13 – Updated: 2026-03-11 20:33
VLAI
Summary
Sylius has a Promotion Usage Limit Bypass via Race Condition
Details
Impact
A Time-of-Check To Time-of-Use (TOCTOU) race condition was discovered in the promotion usage limit enforcement. The same class of vulnerability affects three independent limits:
- Promotion usage limit - the global
usedcounter onPromotionentities - Coupon usage limit - the global
usedcounter onPromotionCouponentities - Coupon per-customer usage limit - the per-customer redemption count on
PromotionCouponentities
In all three cases, the eligibility check reads the used counter (or order count) from an in-memory Doctrine entity during validation, while the actual usage increment in OrderPromotionsUsageModifier happens later during order completion — with no database-level locking or atomic operations between the two phases.
Because Doctrine flushes an absolute value (SET used = 1) rather than an atomic increment (SET used = used + 1), and because the affected entities lack optimistic locking, concurrent requests all read the same stale usage counts and pass the eligibility checks simultaneously.
An attacker can exploit this by preparing multiple carts with the same limited-use promotion or coupon and firing simultaneous PATCH /api/v2/shop/orders/{token}/complete requests. All requests pass the usage limit checks and complete successfully, allowing a single-use promotion or coupon to be redeemed an arbitrary number of times. The per-customer limit can be bypassed in the same way by a single customer completing multiple orders concurrently. No authentication is required to exploit this vulnerability.
This may lead to direct financial loss through unlimited redemption of limited-use promotions and discount coupons.
Patches
The issue is fixed in versions: 1.9.12, 1.10.16, 1.11.17, 1.12.23, 1.13.15, 1.14.18, 2.0.16, 2.1.12, 2.2.3 and above.
Workarounds
Decoration of the OrderPromotionsUsageModifier service to use atomic operations based on actual database-synchronized values.
The decorated service id in Sylius >=2.0 is sylius.modifier.promotion.order_usage, while <2.0 it's sylius.promotion_usage_modifier; The following instruction uses the latter, but it needs to be changed depending on the Sylius version.
Step 1. Create the decorator service
src/Modifier/AtomicOrderPromotionsUsageModifier.php:
<?php
declare(strict_types=1);
namespace App\Modifier;
use Doctrine\DBAL\Connection;
use Doctrine\ORM\OptimisticLockException;
use Sylius\Component\Core\Model\OrderInterface;
use Sylius\Component\Core\Model\PromotionCouponInterface;
use Sylius\Component\Core\Promotion\Modifier\OrderPromotionsUsageModifierInterface;
use Sylius\Component\Promotion\Model\PromotionInterface;
// use Symfony\Component\DependencyInjection\Attribute\AsDecorator;
// #[AsDecorator(decorates: 'sylius.promotion_usage_modifier')]
final class AtomicOrderPromotionsUsageModifier implements OrderPromotionsUsageModifierInterface
{
/** @var Connection */
private $connection;
public function __construct(Connection $connection)
{
$this->connection = $connection;
}
public function increment(OrderInterface $order): void
{
foreach ($order->getPromotions() as $promotion) {
$this->incrementPromotionUsage($promotion);
}
/** @var PromotionCouponInterface|null $coupon */
$coupon = $order->getPromotionCoupon();
if (null === $coupon) {
return;
}
$this->incrementCouponUsage($coupon, $order);
}
public function decrement(OrderInterface $order): void
{
foreach ($order->getPromotions() as $promotion) {
$this->decrementPromotionUsage($promotion);
}
/** @var PromotionCouponInterface|null $coupon */
$coupon = $order->getPromotionCoupon();
if (null === $coupon) {
return;
}
if (OrderInterface::STATE_CANCELLED === $order->getState() && !$coupon->isReusableFromCancelledOrders()) {
return;
}
$this->decrementCouponUsage($coupon);
}
private function incrementPromotionUsage(PromotionInterface $promotion): void
{
$affected = $this->doExecuteStatement(
'UPDATE sylius_promotion
SET used = used + 1
WHERE id = :id AND (usage_limit IS NULL OR used < usage_limit)',
['id' => $promotion->getId()]
);
if (0 === $affected) {
throw new OptimisticLockException(sprintf('Promotion "%s" is no longer applicable.', $promotion->getCode()), $promotion);
}
$newUsed = (int) $this->doFetchOne(
'SELECT used FROM sylius_promotion WHERE id = :id',
['id' => $promotion->getId()]
);
$promotion->setUsed($newUsed);
}
private function decrementPromotionUsage(PromotionInterface $promotion): void
{
$this->doExecuteStatement(
'UPDATE sylius_promotion SET used = GREATEST(used - 1, 0) WHERE id = :id',
['id' => $promotion->getId()]
);
$newUsed = (int) $this->doFetchOne(
'SELECT used FROM sylius_promotion WHERE id = :id',
['id' => $promotion->getId()]
);
$promotion->setUsed($newUsed);
}
private function incrementCouponUsage(PromotionCouponInterface $coupon, OrderInterface $order): void
{
$row = $this->doFetchAssociative(
'SELECT used, usage_limit, per_customer_usage_limit FROM sylius_promotion_coupon WHERE id = :id FOR UPDATE',
['id' => $coupon->getId()]
);
if (false === $row) {
throw new OptimisticLockException(sprintf('Promotion coupon "%s" is no longer applicable.', $coupon->getCode()), $coupon);
}
if (null !== $row['usage_limit'] && (int) $row['used'] >= (int) $row['usage_limit']) {
throw new OptimisticLockException(sprintf('Promotion coupon "%s" is no longer applicable.', $coupon->getCode()), $coupon);
}
if (null !== $row['per_customer_usage_limit']) {
$this->assertPerCustomerCouponUsageLimitNotReached(
$coupon,
$order,
(int) $row['per_customer_usage_limit']
);
}
$this->doExecuteStatement(
'UPDATE sylius_promotion_coupon SET used = used + 1 WHERE id = :id',
['id' => $coupon->getId()]
);
$coupon->setUsed((int) $row['used'] + 1);
}
private function assertPerCustomerCouponUsageLimitNotReached(
PromotionCouponInterface $coupon,
OrderInterface $order,
int $perCustomerUsageLimit
): void {
$customer = $order->getCustomer();
if (null === $customer || null === $customer->getId()) {
return;
}
$sql = 'SELECT o.id FROM sylius_order o
WHERE o.customer_id = :customerId
AND o.promotion_coupon_id = :couponId
AND o.state != :stateCart';
$params = [
'customerId' => $customer->getId(),
'couponId' => $coupon->getId(),
'stateCart' => OrderInterface::STATE_CART,
];
if ($coupon->isReusableFromCancelledOrders()) {
$sql .= ' AND o.state != :stateCancelled';
$params['stateCancelled'] = OrderInterface::STATE_CANCELLED;
}
$sql .= ' FOR UPDATE';
$count = count($this->doFetchAllAssociative($sql, $params));
if ($count >= $perCustomerUsageLimit) {
throw new OptimisticLockException(sprintf('Promotion coupon "%s" is no longer applicable.', $coupon->getCode()), $coupon);
}
}
private function decrementCouponUsage(PromotionCouponInterface $coupon): void
{
$this->doExecuteStatement(
'UPDATE sylius_promotion_coupon SET used = GREATEST(used - 1, 0) WHERE id = :id',
['id' => $coupon->getId()]
);
$newUsed = (int) $this->doFetchOne(
'SELECT used FROM sylius_promotion_coupon WHERE id = :id',
['id' => $coupon->getId()]
);
$coupon->setUsed($newUsed);
}
/** @return int Number of affected rows */
private function doExecuteStatement(string $sql, array $params): int
{
if (method_exists($this->connection, 'executeStatement')) {
return $this->connection->executeStatement($sql, $params);
}
return $this->connection->executeUpdate($sql, $params);
}
/** @return mixed|false */
private function doFetchOne(string $sql, array $params)
{
if (method_exists($this->connection, 'fetchOne')) {
return $this->connection->fetchOne($sql, $params);
}
return $this->connection->fetchColumn($sql, $params);
}
/** @return array|false */
private function doFetchAssociative(string $sql, array $params)
{
if (method_exists($this->connection, 'fetchAssociative')) {
return $this->connection->fetchAssociative($sql, $params);
}
return $this->connection->fetchAssoc($sql, $params);
}
/** @return array[] */
private function doFetchAllAssociative(string $sql, array $params): array
{
if (method_exists($this->connection, 'fetchAllAssociative')) {
return $this->connection->fetchAllAssociative($sql, $params);
}
return $this->connection->fetchAll($sql, $params);
}
}
Step 2. Register the service
Option A: If your app uses autowiring and supports the #[AsDecorator] attribute, uncomment it in the class and no further configuration is necessary.
Option B: Manually register the service in config/services.yaml:
services:
App\Modifier\AtomicOrderPromotionsUsageModifier:
decorates: 'sylius.promotion_usage_modifier'
arguments: ['@doctrine.dbal.default_connection']
Step 3. Update exception mapping (optional)
Check if your api_platform configuration maps OptimisticLockException to a code and update it if not:
api_platform:
...
exception_to_status:
...
Doctrine\ORM\OptimisticLockException: 409
Step 4. Clear cache
bin/console cache:clear
Reporters
We would like to extend our gratitude to the following individuals for their detailed reporting and responsible disclosure of this vulnerability: - Djibril Mounkoro (@whiteov3rflow) - Bartłomiej Nowiński (@bnBart)
For more information
If you have any questions or comments about this advisory:
- Open an issue in Sylius issues
- Email us at security@sylius.com
Severity
8.2 (High)
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.9.11"
},
"package": {
"ecosystem": "Packagist",
"name": "sylius/sylius"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.9.12"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.10.15"
},
"package": {
"ecosystem": "Packagist",
"name": "sylius/sylius"
},
"ranges": [
{
"events": [
{
"introduced": "1.10.0"
},
{
"fixed": "1.10.16"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.11.16"
},
"package": {
"ecosystem": "Packagist",
"name": "sylius/sylius"
},
"ranges": [
{
"events": [
{
"introduced": "1.11.0"
},
{
"fixed": "1.11.17"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.12.22"
},
"package": {
"ecosystem": "Packagist",
"name": "sylius/sylius"
},
"ranges": [
{
"events": [
{
"introduced": "1.12.0"
},
{
"fixed": "1.12.23"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.13.14"
},
"package": {
"ecosystem": "Packagist",
"name": "sylius/sylius"
},
"ranges": [
{
"events": [
{
"introduced": "1.13.0"
},
{
"fixed": "1.13.15"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.14.17"
},
"package": {
"ecosystem": "Packagist",
"name": "sylius/sylius"
},
"ranges": [
{
"events": [
{
"introduced": "1.14.0"
},
{
"fixed": "1.14.18"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.0.15"
},
"package": {
"ecosystem": "Packagist",
"name": "sylius/sylius"
},
"ranges": [
{
"events": [
{
"introduced": "2.0.0"
},
{
"fixed": "2.0.16"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.1.11"
},
"package": {
"ecosystem": "Packagist",
"name": "sylius/sylius"
},
"ranges": [
{
"events": [
{
"introduced": "2.1.0"
},
{
"fixed": "2.1.12"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.2.2"
},
"package": {
"ecosystem": "Packagist",
"name": "sylius/sylius"
},
"ranges": [
{
"events": [
{
"introduced": "2.2.0"
},
{
"fixed": "2.2.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-31824"
],
"database_specific": {
"cwe_ids": [
"CWE-362",
"CWE-367"
],
"github_reviewed": true,
"github_reviewed_at": "2026-03-11T00:13:29Z",
"nvd_published_at": "2026-03-10T22:16:20Z",
"severity": "HIGH"
},
"details": "### Impact\nA Time-of-Check To Time-of-Use (TOCTOU) race condition was discovered in the promotion usage limit enforcement. The same class of vulnerability affects three independent limits:\n\n1. **Promotion usage limit** - the global `used` counter on `Promotion` entities\n2. **Coupon usage limit** - the global `used` counter on `PromotionCoupon` entities\n3. **Coupon per-customer usage limit** - the per-customer redemption count on `PromotionCoupon` entities\n\nIn all three cases, the eligibility check reads the `used` counter (or order count) from an in-memory Doctrine entity during validation, while the actual usage increment in `OrderPromotionsUsageModifier` happens later during order completion \u2014 with no database-level locking or atomic operations between the two phases.\n\nBecause Doctrine flushes an absolute value (`SET used = 1`) rather than an atomic increment (`SET used = used + 1`), and because the affected entities lack optimistic locking, concurrent requests all read the same stale usage counts and pass the eligibility checks simultaneously.\n\nAn attacker can exploit this by preparing multiple carts with the same limited-use promotion or coupon and firing simultaneous `PATCH /api/v2/shop/orders/{token}/complete` requests. All requests pass the usage limit checks and complete successfully, allowing a single-use promotion or coupon to be redeemed an arbitrary number of times. The per-customer limit can be bypassed in the same way by a single customer completing multiple orders concurrently. No authentication is required to exploit this vulnerability.\n\nThis may lead to direct financial loss through unlimited redemption of limited-use promotions and discount coupons.\n\n### Patches\nThe issue is fixed in versions: 1.9.12, 1.10.16, 1.11.17, 1.12.23, 1.13.15, 1.14.18, 2.0.16, 2.1.12, 2.2.3 and above.\n\n### Workarounds\n\nDecoration of the `OrderPromotionsUsageModifier` service to use atomic operations based on actual database-synchronized values.\n\nThe decorated service id in Sylius \u003e=2.0 is `sylius.modifier.promotion.order_usage`, while \u003c2.0 it\u0027s `sylius.promotion_usage_modifier`; The following instruction uses the latter, but it needs to be changed depending on the Sylius version.\n\n#### Step 1. Create the decorator service\n\n`src/Modifier/AtomicOrderPromotionsUsageModifier.php`:\n\n```php\n\u003c?php\n\ndeclare(strict_types=1);\n\nnamespace App\\Modifier;\n\nuse Doctrine\\DBAL\\Connection;\nuse Doctrine\\ORM\\OptimisticLockException;\nuse Sylius\\Component\\Core\\Model\\OrderInterface;\nuse Sylius\\Component\\Core\\Model\\PromotionCouponInterface;\nuse Sylius\\Component\\Core\\Promotion\\Modifier\\OrderPromotionsUsageModifierInterface;\nuse Sylius\\Component\\Promotion\\Model\\PromotionInterface;\n// use Symfony\\Component\\DependencyInjection\\Attribute\\AsDecorator;\n\n// #[AsDecorator(decorates: \u0027sylius.promotion_usage_modifier\u0027)]\nfinal class AtomicOrderPromotionsUsageModifier implements OrderPromotionsUsageModifierInterface\n{\n /** @var Connection */\n private $connection;\n\n public function __construct(Connection $connection)\n {\n $this-\u003econnection = $connection;\n }\n\n public function increment(OrderInterface $order): void\n {\n foreach ($order-\u003egetPromotions() as $promotion) {\n $this-\u003eincrementPromotionUsage($promotion);\n }\n\n /** @var PromotionCouponInterface|null $coupon */\n $coupon = $order-\u003egetPromotionCoupon();\n if (null === $coupon) {\n return;\n }\n\n $this-\u003eincrementCouponUsage($coupon, $order);\n }\n\n public function decrement(OrderInterface $order): void\n {\n foreach ($order-\u003egetPromotions() as $promotion) {\n $this-\u003edecrementPromotionUsage($promotion);\n }\n\n /** @var PromotionCouponInterface|null $coupon */\n $coupon = $order-\u003egetPromotionCoupon();\n if (null === $coupon) {\n return;\n }\n\n if (OrderInterface::STATE_CANCELLED === $order-\u003egetState() \u0026\u0026 !$coupon-\u003eisReusableFromCancelledOrders()) {\n return;\n }\n\n $this-\u003edecrementCouponUsage($coupon);\n }\n\n private function incrementPromotionUsage(PromotionInterface $promotion): void\n {\n $affected = $this-\u003edoExecuteStatement(\n \u0027UPDATE sylius_promotion\n SET used = used + 1\n WHERE id = :id AND (usage_limit IS NULL OR used \u003c usage_limit)\u0027,\n [\u0027id\u0027 =\u003e $promotion-\u003egetId()]\n );\n\n if (0 === $affected) {\n throw new OptimisticLockException(sprintf(\u0027Promotion \"%s\" is no longer applicable.\u0027, $promotion-\u003egetCode()), $promotion);\n }\n\n $newUsed = (int) $this-\u003edoFetchOne(\n \u0027SELECT used FROM sylius_promotion WHERE id = :id\u0027,\n [\u0027id\u0027 =\u003e $promotion-\u003egetId()]\n );\n\n $promotion-\u003esetUsed($newUsed);\n }\n\n private function decrementPromotionUsage(PromotionInterface $promotion): void\n {\n $this-\u003edoExecuteStatement(\n \u0027UPDATE sylius_promotion SET used = GREATEST(used - 1, 0) WHERE id = :id\u0027,\n [\u0027id\u0027 =\u003e $promotion-\u003egetId()]\n );\n\n $newUsed = (int) $this-\u003edoFetchOne(\n \u0027SELECT used FROM sylius_promotion WHERE id = :id\u0027,\n [\u0027id\u0027 =\u003e $promotion-\u003egetId()]\n );\n\n $promotion-\u003esetUsed($newUsed);\n }\n\n private function incrementCouponUsage(PromotionCouponInterface $coupon, OrderInterface $order): void\n {\n $row = $this-\u003edoFetchAssociative(\n \u0027SELECT used, usage_limit, per_customer_usage_limit FROM sylius_promotion_coupon WHERE id = :id FOR UPDATE\u0027,\n [\u0027id\u0027 =\u003e $coupon-\u003egetId()]\n );\n\n if (false === $row) {\n throw new OptimisticLockException(sprintf(\u0027Promotion coupon \"%s\" is no longer applicable.\u0027, $coupon-\u003egetCode()), $coupon);\n }\n\n if (null !== $row[\u0027usage_limit\u0027] \u0026\u0026 (int) $row[\u0027used\u0027] \u003e= (int) $row[\u0027usage_limit\u0027]) {\n throw new OptimisticLockException(sprintf(\u0027Promotion coupon \"%s\" is no longer applicable.\u0027, $coupon-\u003egetCode()), $coupon);\n }\n\n if (null !== $row[\u0027per_customer_usage_limit\u0027]) {\n $this-\u003eassertPerCustomerCouponUsageLimitNotReached(\n $coupon,\n $order,\n (int) $row[\u0027per_customer_usage_limit\u0027]\n );\n }\n\n $this-\u003edoExecuteStatement(\n \u0027UPDATE sylius_promotion_coupon SET used = used + 1 WHERE id = :id\u0027,\n [\u0027id\u0027 =\u003e $coupon-\u003egetId()]\n );\n\n $coupon-\u003esetUsed((int) $row[\u0027used\u0027] + 1);\n }\n\n private function assertPerCustomerCouponUsageLimitNotReached(\n PromotionCouponInterface $coupon,\n OrderInterface $order,\n int $perCustomerUsageLimit\n ): void {\n $customer = $order-\u003egetCustomer();\n if (null === $customer || null === $customer-\u003egetId()) {\n return;\n }\n\n $sql = \u0027SELECT o.id FROM sylius_order o\n WHERE o.customer_id = :customerId\n AND o.promotion_coupon_id = :couponId\n AND o.state != :stateCart\u0027;\n $params = [\n \u0027customerId\u0027 =\u003e $customer-\u003egetId(),\n \u0027couponId\u0027 =\u003e $coupon-\u003egetId(),\n \u0027stateCart\u0027 =\u003e OrderInterface::STATE_CART,\n ];\n\n if ($coupon-\u003eisReusableFromCancelledOrders()) {\n $sql .= \u0027 AND o.state != :stateCancelled\u0027;\n $params[\u0027stateCancelled\u0027] = OrderInterface::STATE_CANCELLED;\n }\n\n $sql .= \u0027 FOR UPDATE\u0027;\n\n $count = count($this-\u003edoFetchAllAssociative($sql, $params));\n\n if ($count \u003e= $perCustomerUsageLimit) {\n throw new OptimisticLockException(sprintf(\u0027Promotion coupon \"%s\" is no longer applicable.\u0027, $coupon-\u003egetCode()), $coupon);\n }\n }\n\n private function decrementCouponUsage(PromotionCouponInterface $coupon): void\n {\n $this-\u003edoExecuteStatement(\n \u0027UPDATE sylius_promotion_coupon SET used = GREATEST(used - 1, 0) WHERE id = :id\u0027,\n [\u0027id\u0027 =\u003e $coupon-\u003egetId()]\n );\n\n $newUsed = (int) $this-\u003edoFetchOne(\n \u0027SELECT used FROM sylius_promotion_coupon WHERE id = :id\u0027,\n [\u0027id\u0027 =\u003e $coupon-\u003egetId()]\n );\n\n $coupon-\u003esetUsed($newUsed);\n }\n\n /** @return int Number of affected rows */\n private function doExecuteStatement(string $sql, array $params): int\n {\n if (method_exists($this-\u003econnection, \u0027executeStatement\u0027)) {\n return $this-\u003econnection-\u003eexecuteStatement($sql, $params);\n }\n\n return $this-\u003econnection-\u003eexecuteUpdate($sql, $params);\n }\n\n /** @return mixed|false */\n private function doFetchOne(string $sql, array $params)\n {\n if (method_exists($this-\u003econnection, \u0027fetchOne\u0027)) {\n return $this-\u003econnection-\u003efetchOne($sql, $params);\n }\n\n return $this-\u003econnection-\u003efetchColumn($sql, $params);\n }\n\n /** @return array|false */\n private function doFetchAssociative(string $sql, array $params)\n {\n if (method_exists($this-\u003econnection, \u0027fetchAssociative\u0027)) {\n return $this-\u003econnection-\u003efetchAssociative($sql, $params);\n }\n\n return $this-\u003econnection-\u003efetchAssoc($sql, $params);\n }\n\n /** @return array[] */\n private function doFetchAllAssociative(string $sql, array $params): array\n {\n if (method_exists($this-\u003econnection, \u0027fetchAllAssociative\u0027)) {\n return $this-\u003econnection-\u003efetchAllAssociative($sql, $params);\n }\n\n return $this-\u003econnection-\u003efetchAll($sql, $params);\n }\n}\n```\n\n#### Step 2. Register the service\n\n**Option A:** If your app uses autowiring and supports the `#[AsDecorator]` attribute, uncomment it in the class and no further configuration is necessary.\n\n**Option B:** Manually register the service in `config/services.yaml`:\n\n```yaml\nservices:\n App\\Modifier\\AtomicOrderPromotionsUsageModifier:\n decorates: \u0027sylius.promotion_usage_modifier\u0027\n arguments: [\u0027@doctrine.dbal.default_connection\u0027]\n```\n\n#### Step 3. Update exception mapping (optional)\n\nCheck if your `api_platform` configuration maps `OptimisticLockException` to a code and update it if not:\n```yaml\napi_platform:\n ...\n exception_to_status:\n ...\n Doctrine\\ORM\\OptimisticLockException: 409\n```\n\n#### Step 4. Clear cache\n\n```bash\nbin/console cache:clear\n```\n\n### Reporters\n\nWe would like to extend our gratitude to the following individuals for their detailed reporting and responsible disclosure of this vulnerability:\n- Djibril Mounkoro (@whiteov3rflow)\n- Bart\u0142omiej Nowi\u0144ski (@bnBart)\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n\n- Open an issue in [Sylius issues](https://github.com/Sylius/Sylius/issues)\n- Email us at [security@sylius.com](mailto:security@sylius.com)",
"id": "GHSA-7mp4-25j8-hp5q",
"modified": "2026-03-11T20:33:38Z",
"published": "2026-03-11T00:13:29Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Sylius/Sylius/security/advisories/GHSA-7mp4-25j8-hp5q"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31824"
},
{
"type": "PACKAGE",
"url": "https://github.com/Sylius/Sylius"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L",
"type": "CVSS_V3"
}
],
"summary": "Sylius has a Promotion Usage Limit Bypass via Race Condition"
}
GHSA-7MQW-HR29-PJ76
Vulnerability from github – Published: 2026-05-13 18:30 – Updated: 2026-05-13 18:30
VLAI
Details
csync2 uses insecure temporary directories when compiled with C99 or later, allowing for TOCTOU style attacks on the temporary directories.
Severity
5.0 (Medium)
{
"affected": [],
"aliases": [
"CVE-2026-41051"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-05-13T13:01:53Z",
"severity": "MODERATE"
},
"details": "csync2 uses insecure temporary directories when compiled with C99 or later, allowing for TOCTOU style attacks on the temporary directories.",
"id": "GHSA-7mqw-hr29-pj76",
"modified": "2026-05-13T18:30:52Z",
"published": "2026-05-13T18:30:52Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-41051"
},
{
"type": "WEB",
"url": "https://bugzilla.suse.com/show_bug.cgi?id=CVE-2026-41051"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-7PMF-JRH8-VG99
Vulnerability from github – Published: 2023-02-15 03:30 – Updated: 2023-02-23 18:31
VLAI
Details
An issue was discovered in Insyde InsydeH2O with kernel 5.1 through 5.5. DMA attacks on the SdMmcDevice buffer used by SMM and non-SMM code could cause TOCTOU race-condition issues that could lead to corruption of SMRAM and escalation of privileges. This attack can be mitigated by using IOMMU protection for the ACPI runtime memory used for the command buffer. This attack can be mitigated by copying the link data to SMRAM before checking it and verifying that all pointers are within the buffer.
Severity
7.0 (High)
{
"affected": [],
"aliases": [
"CVE-2022-32954"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-02-15T02:15:00Z",
"severity": "HIGH"
},
"details": "An issue was discovered in Insyde InsydeH2O with kernel 5.1 through 5.5. DMA attacks on the SdMmcDevice buffer used by SMM and non-SMM code could cause TOCTOU race-condition issues that could lead to corruption of SMRAM and escalation of privileges. This attack can be mitigated by using IOMMU protection for the ACPI runtime memory used for the command buffer. This attack can be mitigated by copying the link data to SMRAM before checking it and verifying that all pointers are within the buffer.",
"id": "GHSA-7pmf-jrh8-vg99",
"modified": "2023-02-23T18:31:05Z",
"published": "2023-02-15T03:30:46Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-32954"
},
{
"type": "WEB",
"url": "https://www.insyde.com/security-pledge"
},
{
"type": "WEB",
"url": "https://www.insyde.com/security-pledge/SA-2023014"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-7PRC-4C75-54X8
Vulnerability from github – Published: 2025-06-16 09:30 – Updated: 2025-06-17 03:31
VLAI
Details
A race condition vulnerability exists in Armoury Crate. This vulnerability arises from a Time-of-check Time-of-use issue, potentially leading to authentication bypass. Refer to the 'Security Update for Armoury Crate App' section on the ASUS Security Advisory for more information.
Severity
{
"affected": [],
"aliases": [
"CVE-2025-3464"
],
"database_specific": {
"cwe_ids": [
"CWE-367"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-06-16T09:15:19Z",
"severity": "HIGH"
},
"details": "A race condition vulnerability exists in Armoury Crate. This vulnerability arises from a Time-of-check Time-of-use issue, potentially leading to authentication bypass.\nRefer to the \u0027Security Update for Armoury Crate App\u0027 section on the ASUS Security Advisory for more information.",
"id": "GHSA-7prc-4c75-54x8",
"modified": "2025-06-17T03:31:44Z",
"published": "2025-06-16T09:30:38Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-3464"
},
{
"type": "WEB",
"url": "https://talosintelligence.com/vulnerability_reports/TALOS-2024-2150"
},
{
"type": "WEB",
"url": "https://talosintelligence.com/vulnerability_reports/TALOS-2025-2150"
},
{
"type": "WEB",
"url": "https://www.asus.com/content/asus-product-security-advisory"
},
{
"type": "WEB",
"url": "https://www.talosintelligence.com/vulnerability_reports/TALOS-2025-2150"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:H/VA:H/SC:L/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-7QF6-H84J-8FQ4
Vulnerability from github – Published: 2026-03-03 22:21 – Updated: 2026-03-03 22:21
VLAI
Summary
OpenClaw: Microsoft Teams media fetch paths bypass shared SSRF guard model
Details
Impact
Microsoft Teams media handling used mixed fetch paths for Graph metadata/content and attachment auth-retry flows. Some paths bypassed the shared SSRF guard model and created inconsistent host/DNS enforcement across redirect/fetch hops.
Affected Packages / Versions
- Package:
openclaw(npm) - Latest published vulnerable version:
2026.2.25 - Affected range:
<= 2026.2.25 - Planned patched version for next release:
2026.2.26
Technical Details
The Microsoft Teams attachment/media code previously relied on plugin-local fetch behavior in parts of the flow, instead of uniformly using shared guarded fetch logic with pinned DNS + policy checks. This could allow policy drift and SSRF boundary inconsistency between channel/plugin paths.
The fix unifies this path by:
- routing Microsoft Teams Graph message/hosted-content/attachment fetches through shared SSRF-guarded fetch paths,
- routing auth-scope fallback attachment downloads through the same guarded policy model,
- centralizing hostname-suffix allowlist policy helpers in plugin-sdk so channel/plugins use the same allowlist normalization and policy construction behavior.
Fix Commit(s)
57334cd7d85174d5f951de01114fd5801b063564
OpenClaw thanks @tdjackey for reporting.
Severity
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2026.2.25"
},
"package": {
"ecosystem": "npm",
"name": "openclaw"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2026.2.26"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-367",
"CWE-918"
],
"github_reviewed": true,
"github_reviewed_at": "2026-03-03T22:21:59Z",
"nvd_published_at": null,
"severity": "LOW"
},
"details": "## Impact\nMicrosoft Teams media handling used mixed fetch paths for Graph metadata/content and attachment auth-retry flows. Some paths bypassed the shared SSRF guard model and created inconsistent host/DNS enforcement across redirect/fetch hops.\n\n## Affected Packages / Versions\n- Package: `openclaw` (npm)\n- Latest published vulnerable version: `2026.2.25`\n- Affected range: `\u003c= 2026.2.25`\n- Planned patched version for next release: `2026.2.26`\n\n## Technical Details\nThe Microsoft Teams attachment/media code previously relied on plugin-local fetch behavior in parts of the flow, instead of uniformly using shared guarded fetch logic with pinned DNS + policy checks. This could allow policy drift and SSRF boundary inconsistency between channel/plugin paths.\n\nThe fix unifies this path by:\n- routing Microsoft Teams Graph message/hosted-content/attachment fetches through shared SSRF-guarded fetch paths,\n- routing auth-scope fallback attachment downloads through the same guarded policy model,\n- centralizing hostname-suffix allowlist policy helpers in `plugin-sdk` so channel/plugins use the same allowlist normalization and policy construction behavior.\n\n## Fix Commit(s)\n- `57334cd7d85174d5f951de01114fd5801b063564`\n\nOpenClaw thanks @tdjackey for reporting.",
"id": "GHSA-7qf6-h84j-8fq4",
"modified": "2026-03-03T22:21:59Z",
"published": "2026-03-03T22:21:59Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/openclaw/openclaw/security/advisories/GHSA-7qf6-h84j-8fq4"
},
{
"type": "WEB",
"url": "https://github.com/openclaw/openclaw/commit/57334cd7d85174d5f951de01114fd5801b063564"
},
{
"type": "PACKAGE",
"url": "https://github.com/openclaw/openclaw"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "OpenClaw: Microsoft Teams media fetch paths bypass shared SSRF guard model"
}
Mitigation
Implementation
The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.
Mitigation
Implementation
When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.
Mitigation
Architecture and Design
Limit the interleaving of operations on files from multiple processes.
Mitigation
Implementation
Architecture and Design
If you cannot perform operations atomically and you must share access to the resource between multiple processes or threads, then try to limit the amount of time (CPU cycles) between the check and use of the resource. This will not fix the problem, but it could make it more difficult for an attack to succeed.
Mitigation
Implementation
Recheck the resource after the use call to verify that the action was taken appropriately.
Mitigation
Architecture and Design
Ensure that some environmental locking mechanism can be used to protect resources effectively.
Mitigation
Implementation
Ensure that locking occurs before the check, as opposed to afterwards, such that the resource, as checked, is the same as it is when in use.
CAPEC-27: Leveraging Race Conditions via Symbolic Links
This attack leverages the use of symbolic links (Symlinks) in order to write to sensitive files. An attacker can create a Symlink link to a target file not otherwise accessible to them. When the privileged program tries to create a temporary file with the same name as the Symlink link, it will actually write to the target file pointed to by the attackers' Symlink link. If the attacker can insert malicious content in the temporary file they will be writing to the sensitive file by using the Symlink. The race occurs because the system checks if the temporary file exists, then creates the file. The attacker would typically create the Symlink during the interval between the check and the creation of the temporary file.
CAPEC-29: Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions
This attack targets a race condition occurring between the time of check (state) for a resource and the time of use of a resource. A typical example is file access. The adversary can leverage a file access race condition by "running the race", meaning that they would modify the resource between the first time the target program accesses the file and the time the target program uses the file. During that period of time, the adversary could replace or modify the file, causing the application to behave unexpectedly.