{"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":"2026-09-13T06:28:29.166Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-13T06:28:29.166Z"},"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seg_map bit\nand calling cache_seg_get() is unreasonable since the corresponding\nsegment data is no longer valid.\n\nFix both issues by moving cache_seg_get() and __set_bit() after the\ngen check, so they only execute for valid keys, and using continue to\nskip invalid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-rc1","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-rc1"}]}]}],"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"}}}}