CVE-2026-74689 (GCVE-0-2026-74689)
Vulnerability from cvelistv5
Published
2026-08-22 15:32
Modified
2026-08-25 05:41
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/atm: fix slab-out-of-bounds read in vcc_setsockopt()
vcc_setsockopt() contained an ineffective optlen check:
if (__SO_LEVEL_MATCH(optname, level) && optlen != __SO_SIZE(optname))
return -EINVAL;
If __SO_LEVEL_MATCH(optname, level) evaluated to false (e.g. if the caller
passed a mismatched level), the length check optlen != __SO_SIZE(optname)
was short-circuited and bypassed. Execution then fell through to switch(optname),
calling copy_from_sockptr() assuming optval contained sufficient space.
Furthermore, even if level matched, a cgroup BPF setsockopt filter could shrink
optlen after entry. Because copy_from_sockptr() on kernel pointers uses memcpy(),
this leads to a KASAN slab-out-of-bounds read when optlen is smaller than the
expected structure size.
Fix this by using copy_safe_from_sockptr(), which unconditionally validates
that optlen is at least the expected size before copying. Also change the local
'value' variable type from 'unsigned long' to 'int' so that SO_SETCLP matches
its sizeof(int) ABI encoding on 64-bit systems.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/atm/common.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
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"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
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"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
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"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
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"status": "affected",
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"versionType": "git"
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{
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"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/atm/common.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.12"
},
{
"lessThan": "2.6.12",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.152",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.104",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.45",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.9",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.183",
"versionStartIncluding": "2.6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.152",
"versionStartIncluding": "2.6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.45",
"versionStartIncluding": "2.6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.9",
"versionStartIncluding": "2.6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "2.6.12",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/atm: fix slab-out-of-bounds read in vcc_setsockopt()\n\nvcc_setsockopt() contained an ineffective optlen check:\n if (__SO_LEVEL_MATCH(optname, level) \u0026\u0026 optlen != __SO_SIZE(optname))\n return -EINVAL;\n\nIf __SO_LEVEL_MATCH(optname, level) evaluated to false (e.g. if the caller\npassed a mismatched level), the length check optlen != __SO_SIZE(optname)\nwas short-circuited and bypassed. Execution then fell through to switch(optname),\ncalling copy_from_sockptr() assuming optval contained sufficient space.\n\nFurthermore, even if level matched, a cgroup BPF setsockopt filter could shrink\noptlen after entry. Because copy_from_sockptr() on kernel pointers uses memcpy(),\nthis leads to a KASAN slab-out-of-bounds read when optlen is smaller than the\nexpected structure size.\n\nFix this by using copy_safe_from_sockptr(), which unconditionally validates\nthat optlen is at least the expected size before copying. Also change the local\n\u0027value\u0027 variable type from \u0027unsigned long\u0027 to \u0027int\u0027 so that SO_SETCLP matches\nits sizeof(int) ABI encoding on 64-bit systems."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.1,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The bug is reached only via the local setsockopt(2) syscall on an AF_ATMPVC/AF_ATMSVC socket (do_sock_setsockopt -\u003e pvc_setsockopt/svc_setsockopt -\u003e vcc_setsockopt); no remote ATM packet or network-facing handler invokes this path.\nAC:L - The attacker fully controls level, optname, and optlen; passing a mismatched level bypasses the short-circuited length check, and cgroup BPF setsockopt can shrink optlen after entry, deterministically triggering a full-size memcpy past a small kmalloc buffer with no race.\nPR:L - No capability check guards SO_ATMQOS or SO_SETCLP on unconnected ATM sockets; any unprivileged local user in init_net (required because ATM socket creation rejects non-init network namespaces) can open AF_ATMPVC sockets and issue the crafted setsockopt without CAP_NET_ADMIN.\nUI:N - The attacker triggers the out-of-bounds read entirely from their own process with a single crafted setsockopt call; no victim interaction or cooperation is required.\nS:U - Impact is kernel heap memory disclosure and potential crash within the host kernel security boundary; no VM escape, IOMMU bypass, or cross-sandbox boundary crossing occurs.\nC:H - copy_from_sockptr() performs a slab-out-of-bounds read of up to 92 bytes (struct atm_qos) or 8 bytes (SO_SETCLP) past a kmalloc buffer into kernel stack memory; adjacent slab contents can populate vcc-\u003eqos and be retrieved via subsequent SO_ATMQOS getsockopt.\nI:N - The defect is a pure out-of-bounds read with no arbitrary kernel write, heap corruption, or control-flow hijack primitive; although leaked bytes may influence vcc-\u003eqos if validation passes, no attacker-controlled data modification occurs.\nA:H - The KASAN-reported slab-out-of-bounds read triggers kernel oops on hardened kernels, and reading past a small kmalloc object into adjacent slab memory on production kernels risks faulting on unmapped redzone pages or corrupting adjacent objects leading to panic."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-25T05:41:33.932Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/b3bcd5d65ac03c15787b2a5b36c718e26a689336"
},
{
"url": "https://git.kernel.org/stable/c/35f258fee9ed358c6d0f57f91c30bf029c3724af"
},
{
"url": "https://git.kernel.org/stable/c/6eb6af88710977eb529b558a07294874d8c40c4d"
},
{
"url": "https://git.kernel.org/stable/c/9f77c1ab382188f5b51982fab6d913443b6dc59f"
},
{
"url": "https://git.kernel.org/stable/c/2c5988c7349c0b64a7e0441bfc6e1dca54f7116a"
},
{
"url": "https://git.kernel.org/stable/c/d0c80dbb970439bd2eeb0e5effff8c16a5f4e1e3"
}
],
"title": "net/atm: fix slab-out-of-bounds read in vcc_setsockopt()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74689",
"datePublished": "2026-08-22T15:32:54.034Z",
"dateReserved": "2026-08-15T05:44:03.926Z",
"dateUpdated": "2026-08-25T05:41:33.932Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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