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vuln-cve/data/2026/80xxx/CVE-2026-80955.json
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{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2026-80955",
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"state": "PUBLISHED",
"assignerShortName": "Linux",
"dateReserved": "2026-08-26T14:34:25.804Z",
"datePublished": "2026-09-11T19:42:23.838Z",
"dateUpdated": "2026-10-19T08:45:39.156Z"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux",
"dateUpdated": "2026-10-19T08:45:39.156Z"
},
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndm-pcache: fix use-after-free and invalid seg operations in kset_replay()\n\nIn kset_replay, when key->seg_gen is stale (key->seg_gen <\nkey->cache_pos.cache_seg->gen), cache_key_put(key) is called but then\nkey->cache_pos.cache_seg is accessed as the argument to cache_seg_get().\nThis is a use-after-free on the freed key memory. Although mempool\nrecycled memory is not immediately reclaimed or overwritten in practice,\nthis is still a potential UAF bug.\n\nAdditionally, for expired invalid keys, setting the cache->seg_map bit\nand calling cache_seg_get() is unreasonable since the corresponding\nsegment data is no longer valid.\n\nFix both issues by moving cache_seg_get() and __set_bit() after the\ngen check, so they only execute for valid keys, and using continue to\nskip invalid keys."
}
],
"metrics": [
{
"cvssV3_1": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"baseScore": 7.8,
"baseSeverity": "HIGH"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The UAF is reached only via local device-mapper ioctls on /dev/mapper/control (ctl_ioctl → table_load → dm_pcache_ctr → pcache_start → pcache_cache_start → cache_init_req_keys → cache_replay → kset_replay). No network, Bluetooth, or physical-bus path feeds this replay code.\nAC:L - The attacker fully controls the DAX cache-device image, including kset records (CRC uses public PCACHE_CRC_SEED 0x3B15A) and per-segment gen metadata, so they can deterministically encode keys with seg_gen < cache_seg->gen and hit the free-then-use on every table load; no race or victim-side state is required.\nPR:L - ctl_ioctl gates DM_TABLE_LOAD with capable(CAP_SYS_ADMIN), which is obtainable inside an unprivileged user namespace (and in storage containers with delegated mapper/DAX nodes); per kernel CNA guidance that is Low, not init-namespace root only.\nUI:N - Exploitation requires only the attacker's own dmsetup/DM_TABLE_LOAD of a pcache target whose cache device holds crafted INIT_DONE ksets; no separate victim must mount media, open a file, or otherwise interact.\nS:U - The use-after-free is of a pcache_cache_key in the req_key_tree mempool and of cache seg_map/segment refcounts inside the host kernel; it does not cross a VM, hypervisor, IOMMU, or other separate security-authority boundary.\nC:H - On a stale key, cache_key_put() mempool-frees the decoded pcache_cache_key and kset_replay then reads key->cache_pos.cache_seg from that freed heap object. A kernel UAF of a slab/mempool object enables reclaim and an arbitrary read primitive, so confidentiality is High.\nI:H - The dangling key is passed to cache_seg_get(), which atomic_inc()s refs on the pointer loaded from freed memory, and the stale path also __set_bit()s cache->seg_map before the gen check. That UAF write/refcount primitive is Integrity High and is exploitable for control-flow hijack after spraying.\nA:H - Using the freed cache key (and inflating segment refs plus seg_map bits for invalid keys) can oops or panic on poisoned/reused mempool memory or under KASAN/slub debug; any kernel crash from this UAF is Availability High."
}
]
}
],
"affected": [
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"drivers/md/dm-pcache/cache_key.c"
],
"versions": [
{
"version": "1d57628ff95b32d5cfa8d8f50e07690c161e9cf0",
"lessThan": "1894fc7a3bab90143dcd26ef8ee27040ef4a7501",
"status": "affected",
"versionType": "git"
},
{
"version": "1d57628ff95b32d5cfa8d8f50e07690c161e9cf0",
"lessThan": "f39a3e9cc5946473e16d6f5071b2ee0216c56d06",
"status": "affected",
"versionType": "git"
},
{
"version": "1d57628ff95b32d5cfa8d8f50e07690c161e9cf0",
"lessThan": "c2e894eac398b258f12fdec73ed6ba081047f7b3",
"status": "affected",
"versionType": "git"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"drivers/md/dm-pcache/cache_key.c"
],
"versions": [
{
"version": "6.18",
"status": "affected"
},
{
"version": "0",
"lessThan": "6.18",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.18.50",
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "7.2.4",
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"operator": "OR",
"negate": false,
"cpeMatch": [
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.18",
"versionEndExcluding": "6.18.50"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.18",
"versionEndExcluding": "7.2.4"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.18",
"versionEndExcluding": "7.3"
}
]
}
]
}
],
"references": [
{
"url": "https://git.kernel.org/stable/c/1894fc7a3bab90143dcd26ef8ee27040ef4a7501"
},
{
"url": "https://git.kernel.org/stable/c/f39a3e9cc5946473e16d6f5071b2ee0216c56d06"
},
{
"url": "https://git.kernel.org/stable/c/c2e894eac398b258f12fdec73ed6ba081047f7b3"
}
],
"title": "dm-pcache: fix use-after-free and invalid seg operations in kset_replay()",
"x_generator": {
"engine": "bippy-1.2.0"
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}
}