CVE-2026-74590 (GCVE-0-2026-74590)
Vulnerability from cvelistv5
Published
2026-08-22 15:31
Modified
2026-08-25 05:40
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
fsverity: Fix bpf_get_fsverity_digest() dynptr assumptions
The BPF verifier and the dynptr abstraction ensure that the memory space
referenced by a dynptr remains valid. They do not, however, provide any
guarantee that the contents of the memory are stable. kfuncs are
expected to remain memory-safe even if concurrent modifications occur.
bpf_get_fsverity_digest() didn't follow that: it could crash if
arg->digest_size was concurrently modified.
Fix that by using the known-good value hash_alg->digest_size instead.
Also widen 'dynptr_sz' and 'out_digest_sz' to u64 to match the return
type of __bpf_dynptr_size(). It doesn't appear that it can actually be
more than INT_MAX currently (since __bpf_dynptr_data_rw() excludes
file-based pointers), but the correct type might as well be used.
References
| URL | Tags | |
|---|---|---|
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/verity/measure.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "1344b632cb5043e32939a84568125719111c5af3",
"status": "affected",
"version": "67814c00de3161181cddd06c77aeaf86ac4cc584",
"versionType": "git"
},
{
"lessThan": "2a5cfcad1d56e26d645b7887b0ed24c371851525",
"status": "affected",
"version": "67814c00de3161181cddd06c77aeaf86ac4cc584",
"versionType": "git"
},
{
"lessThan": "5bd63cad9df4328a184c409fbdad4f17944bcdb8",
"status": "affected",
"version": "67814c00de3161181cddd06c77aeaf86ac4cc584",
"versionType": "git"
},
{
"lessThan": "3e8ec7c0387273329374f5c7bd61f5f38af71fe1",
"status": "affected",
"version": "67814c00de3161181cddd06c77aeaf86ac4cc584",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/verity/measure.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.8"
},
{
"lessThan": "6.8",
"status": "unaffected",
"version": "0",
"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": "6.12.104",
"versionStartIncluding": "6.8",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.45",
"versionStartIncluding": "6.8",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.9",
"versionStartIncluding": "6.8",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "6.8",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfsverity: Fix bpf_get_fsverity_digest() dynptr assumptions\n\nThe BPF verifier and the dynptr abstraction ensure that the memory space\nreferenced by a dynptr remains valid. They do not, however, provide any\nguarantee that the contents of the memory are stable. kfuncs are\nexpected to remain memory-safe even if concurrent modifications occur.\n\nbpf_get_fsverity_digest() didn\u0027t follow that: it could crash if\narg-\u003edigest_size was concurrently modified.\n\nFix that by using the known-good value hash_alg-\u003edigest_size instead.\n\nAlso widen \u0027dynptr_sz\u0027 and \u0027out_digest_sz\u0027 to u64 to match the return\ntype of __bpf_dynptr_size(). It doesn\u0027t appear that it can actually be\nmore than INT_MAX currently (since __bpf_dynptr_data_rw() excludes\nfile-based pointers), but the correct type might as well be used."
}
],
"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 bug is only reachable via bpf_get_fsverity_digest(), a BPF kfunc callable from BPF LSM programs loaded through the bpf(2) syscall and triggered by local LSM hooks such as file_open, not by any network-facing kernel service.\nAC:L - Exploitation requires racing concurrent writes to the dynptr-backed fsverity_digest buffer (e.g., bpf_map_update_elem from a sibling thread) against the kfunc\u0027s memset; the attacker controls both sides of this race and can repeat it until the bad offset is hit.\nPR:L - Loading and attaching the required BPF LSM program needs CAP_BPF and CAP_PERFMON, which an unprivileged user can obtain as root inside a user namespace (unshare -Ur) without init-namespace privileges, matching kernel CNA guidance for BPF reachability.\nUI:N - No victim interaction is required; the attacker can load the LSM program, prepare a shared dynptr buffer, enable fsverity on a file they own, and trigger file_open themselves to invoke the vulnerable kfunc.\nS:U - Successful exploitation corrupts kernel heap memory and can yield local privilege escalation within the same kernel/host security boundary; it does not by itself cross a guest-to-host, sandbox, or IOMMU isolation boundary.\nC:H - Concurrent tampering with digest_size lets memset() use an attacker-chosen offset beyond the dynptr allocation, causing out-of-bounds kernel heap writes that can corrupt adjacent objects and be leveraged for arbitrary kernel memory disclosure.\nI:H - The faulty memset() can write large zeroed regions far outside the dynptr buffer, giving a controllable out-of-bounds heap write primitive that is exploitable for control-flow hijacking and arbitrary kernel code execution.\nA:H - An out-of-bounds heap write from kernel context can immediately oops/panic the kernel or destabilize critical structures, and the underlying memory corruption reliably threatens system availability even before full exploitation."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-25T05:40:17.568Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/1344b632cb5043e32939a84568125719111c5af3"
},
{
"url": "https://git.kernel.org/stable/c/2a5cfcad1d56e26d645b7887b0ed24c371851525"
},
{
"url": "https://git.kernel.org/stable/c/5bd63cad9df4328a184c409fbdad4f17944bcdb8"
},
{
"url": "https://git.kernel.org/stable/c/3e8ec7c0387273329374f5c7bd61f5f38af71fe1"
}
],
"title": "fsverity: Fix bpf_get_fsverity_digest() dynptr assumptions",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74590",
"datePublished": "2026-08-22T15:31:41.929Z",
"dateReserved": "2026-08-15T05:44:03.918Z",
"dateUpdated": "2026-08-25T05:40:17.568Z",
"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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