CVE-2025-40047 (GCVE-0-2025-40047)
Vulnerability from cvelistv5 – Published: 2025-10-28 11:48 – Updated: 2026-08-05 12:07
VLAI
EPSS
VEX
Title
io_uring/waitid: always prune wait queue entry in io_waitid_wait()
Summary
In the Linux kernel, the following vulnerability has been resolved:
io_uring/waitid: always prune wait queue entry in io_waitid_wait()
For a successful return, always remove our entry from the wait queue
entry list. Previously this was skipped if a cancelation was in
progress, but this can race with another invocation of the wait queue
entry callback.
Severity
7.8 (High)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
f31ecf671ddc498f20219453395794ff2383e06b , < 696ba6032081e617564a8113a001b8d7943cb928
(git)
Affected: f31ecf671ddc498f20219453395794ff2383e06b , < 3e2205db2f0608898d535da1964e1b376aacfdaa (git) Affected: f31ecf671ddc498f20219453395794ff2383e06b , < 2f8229d53d984c6a05b71ac9e9583d4354e3b91f (git) |
guessed | |
| Linux | Linux |
Affected:
6.7
Unaffected: 0 , < 6.7 (semver) Unaffected: 6.12.53 , ≤ 6.12.* (semver) Unaffected: 6.17.3 , ≤ 6.17.* (semver) Unaffected: 6.18 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"io_uring/waitid.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "696ba6032081e617564a8113a001b8d7943cb928",
"status": "affected",
"version": "f31ecf671ddc498f20219453395794ff2383e06b",
"versionType": "git"
},
{
"lessThan": "3e2205db2f0608898d535da1964e1b376aacfdaa",
"status": "affected",
"version": "f31ecf671ddc498f20219453395794ff2383e06b",
"versionType": "git"
},
{
"lessThan": "2f8229d53d984c6a05b71ac9e9583d4354e3b91f",
"status": "affected",
"version": "f31ecf671ddc498f20219453395794ff2383e06b",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"io_uring/waitid.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.7"
},
{
"lessThan": "6.7",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.53",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.17.*",
"status": "unaffected",
"version": "6.17.3",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.18",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.53",
"versionStartIncluding": "6.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.17.3",
"versionStartIncluding": "6.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18",
"versionStartIncluding": "6.7",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/waitid: always prune wait queue entry in io_waitid_wait()\n\nFor a successful return, always remove our entry from the wait queue\nentry list. Previously this was skipped if a cancelation was in\nprogress, but this can race with another invocation of the wait queue\nentry callback."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The vulnerability is reached through the io_uring syscall interface (`io_uring_setup`/`io_uring_enter` submitting an `IORING_OP_WAITID` SQE) plus process-management signals, all of which require local access to the system. Per kernel scoring guidance, io_uring bugs are Local.\nAC:L - The attacker controls both sides of the race: it drives the wait-queue wakeups at arbitrary rate by forking children and looping SIGSTOP/SIGCONT (`do_notify_parent_cldstop` \u2192 `__wake_up_parent`), while concurrently submitting `IORING_OP_ASYNC_CANCEL` or tearing down the ring from another thread to grab the competing reference. syzbot produced a working reproducer and confirmed the fix, showing the window is hit reliably.\nPR:L - Any unprivileged local user can create an io_uring ring \u2014 `sysctl_io_uring_disabled` defaults to 0 and `IORING_OP_WAITID` carries no capability check \u2014 and waiting on one\u0027s own forked children needs no privilege at all. No capabilities, user namespaces, or root are required.\nUI:N - The attacker\u0027s own process performs every step: submitting the waitid SQE, forking and signalling the children that generate wakeups, and issuing the concurrent cancel. No action by any other user is needed.\nS:U - The use-after-free corrupts kernel heap memory and control flow within the same kernel security authority, yielding standard local privilege escalation. No VM, IOMMU, or other security-boundary crossing is involved.\nC:H - This is a use-after-free on a `struct io_waitid_async` allocated from a general-purpose kmalloc slab, which the attacker can reclaim and shape via heap spraying. The stale wait-queue entry is then dereferenced by `__wake_up_common()` and `list_del_init()`, giving a read primitive over reclaimed kernel memory that can be leveraged for arbitrary kernel memory disclosure.\nI:H - `list_del_init()` on the freed entry performs `prev-\u003enext = next; next-\u003eprev = prev` using pointers read from attacker-reclaimed memory, yielding a controlled write of a controlled pointer to a controlled address. Additionally `__wake_up_common()` calls `curr-\u003efunc(...)` on the freed entry, providing a direct indirect-call/control-flow hijack primitive leading to kernel code execution.\nA:H - Even without weaponization, the dangling wait-queue entry and the list-corrupting `list_del_init()` on freed memory produce KASAN splats, list debug BUGs, and kernel oopses/panics \u2014 this is exactly how syzbot detected it. The race can be re-triggered in a tight loop, so an unprivileged user can crash the machine at will."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-05T12:07:20.600Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/696ba6032081e617564a8113a001b8d7943cb928"
},
{
"url": "https://git.kernel.org/stable/c/3e2205db2f0608898d535da1964e1b376aacfdaa"
},
{
"url": "https://git.kernel.org/stable/c/2f8229d53d984c6a05b71ac9e9583d4354e3b91f"
}
],
"title": "io_uring/waitid: always prune wait queue entry in io_waitid_wait()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2025-40047",
"datePublished": "2025-10-28T11:48:24.625Z",
"dateReserved": "2025-04-16T07:20:57.156Z",
"dateUpdated": "2026-08-05T12:07:20.600Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2025-40047",
"date": "2026-09-25",
"epss": "0.00152",
"percentile": "0.03663"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"io_uring/waitid.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "696ba6032081e617564a8113a001b8d7943cb928",
"status": "affected",
"version": "f31ecf671ddc498f20219453395794ff2383e06b",
"versionType": "git"
},
{
"lessThan": "3e2205db2f0608898d535da1964e1b376aacfdaa",
"status": "affected",
"version": "f31ecf671ddc498f20219453395794ff2383e06b",
"versionType": "git"
},
{
"lessThan": "2f8229d53d984c6a05b71ac9e9583d4354e3b91f",
"status": "affected",
"version": "f31ecf671ddc498f20219453395794ff2383e06b",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"io_uring/waitid.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.7"
},
{
"lessThan": "6.7",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.53",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.17.*",
"status": "unaffected",
"version": "6.17.3",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.18",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/waitid: always prune wait queue entry in io_waitid_wait()\n\nFor a successful return, always remove our entry from the wait queue\nentry list. Previously this was skipped if a cancelation was in\nprogress, but this can race with another invocation of the wait queue\nentry callback."
}
],
"id": "CVE-2025-40047",
"lastModified": "2026-07-30T06:24:08.173",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2025-10-28T12:15:38.793",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/2f8229d53d984c6a05b71ac9e9583d4354e3b91f"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/3e2205db2f0608898d535da1964e1b376aacfdaa"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/696ba6032081e617564a8113a001b8d7943cb928"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Deferred"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-07-30T08:53:13+00:00",
"cve": "CVE-2025-40047",
"id": "CVE-2025-40047",
"initial_release_date": "2025-10-28T00:00:00+00:00",
"product_status:fixed": "1224",
"product_status:known_affected": "22",
"product_status:known_not_affected": "90",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: io_uring/waitid: always prune wait queue entry in io_waitid_wait()",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40047.json",
"version": "3"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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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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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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