{ "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seg_map bit\nand calling cache_seg_get() is unreasonable since the corresponding\nsegment data is no longer valid.\n\nFix both issues by moving cache_seg_get() and __set_bit() after the\ngen check, so they only execute for valid keys, and using continue to\nskip invalid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" } } } }