{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80961","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-08-26T14:34:25.809Z","datePublished":"2026-09-11T19:42:27.847Z","dateUpdated":"2026-09-13T06:28:32.873Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-13T06:28:32.873Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ndm-pcache: validate kset key_num and intra-segment bounds\n\nTwo more fields decoded from the cache device go unbounded. The kset\nkey_num drives cache_kset_crc() and the replay loop in cache_replay(),\nthe writeback worker and the GC worker, but only the magic and a\nfixed-seed CRC are checked first, so a non-last kset whose key_num exceeds\nthe PCACHE_KSET_KEYS_MAX buffer reads past its end before the CRC compare.\nA key's intra-segment offset and length in cache_key_decode() are taken\nverbatim, so a key running past its segment is replayed into the cache\ntree and the data CRC check and every later read hit then copy adjacent\npersistent memory into the caller's bio -- an out-of-bounds read that\nleaks to user space. Both fields are controlled by whoever supplies the\ncache device (CAP_SYS_ADMIN); the CRC seed is public.\n\nAdd kset_onmedia_valid() to bound key_num before any kset read, and\nreject a key whose offset plus length, computed in 64 bits, exceeds the\nsegment data_size. Valid metadata is unaffected."}],"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 bugs are reached only via local device-mapper ioctls on /dev/mapper/control (ctl_ioctl → table_load → dm_pcache_ctr → pcache_cache_start → cache_replay) and the subsequent local GC/writeback workers and bio map path; no network protocol or physical-bus input feeds kset/key decode.\nAC:L - The attacker fully controls the DAX cache image; kset CRC uses public PCACHE_CRC_SEED 0x3B15A, so a non-last kset with key_num > 128 and keys whose cache_seg_off+len exceed the segment are encoded and replayed deterministically on table load with no race or victim-side state.\nPR:L - ctl_ioctl gates DM_TABLE_LOAD with capable(CAP_SYS_ADMIN), which per kernel CNA guidance is obtainable inside an unprivileged user namespace and in storage containers with delegated mapper/DAX nodes, so this is Low rather than 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, then optional reads of the mapped device; no separate victim must mount media or open files.\nS:U - The out-of-bounds kset/key access corrupts and discloses memory inside the host kernel that loaded the pcache table; it does not cross a VM, hypervisor, IOMMU, or other separate security-authority boundary.\nC:H - cache_kset_crc() reads struct_size(..., key_num) bytes from a buffer sized for 128 keys, an unbounded kernel-heap OOB read; keys with unchecked cache_seg_off+len are then copied by segment_copy_to_bio() from adjacent pmem/kernel memory into the caller's bio, leaking to userspace.\nI:H - Replay inserts those OOB keys into the cache tree; writeback then copies from the attacker-chosen cache addresses onto the backing device, and later cut/advance of those keys operates on corrupted cache_pos. This OOB memory-corruption class is Integrity High under kernel CNA guidance.\nA:H - An oversized key_num makes crc32c walk off the kset buffer into unmapped heap, writeback BUG_ON(seg_remain < key->len), and cache_pos_advance() BUG_ON or a copy past the DAX mapping can oops or panic the kernel, causing system-wide denial of service."}]}],"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.h","drivers/md/dm-pcache/cache_gc.c","drivers/md/dm-pcache/cache_key.c","drivers/md/dm-pcache/cache_writeback.c"],"versions":[{"version":"1d57628ff95b32d5cfa8d8f50e07690c161e9cf0","lessThan":"d8caf96040a06096276ab72f5e1e8547c014c564","status":"affected","versionType":"git"},{"version":"1d57628ff95b32d5cfa8d8f50e07690c161e9cf0","lessThan":"5ac38f4b4862fad6e7270fde5c3356a822ce74ca","status":"affected","versionType":"git"},{"version":"1d57628ff95b32d5cfa8d8f50e07690c161e9cf0","lessThan":"f11deb032fd84081e7831cffcba895d893054a22","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.h","drivers/md/dm-pcache/cache_gc.c","drivers/md/dm-pcache/cache_key.c","drivers/md/dm-pcache/cache_writeback.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/d8caf96040a06096276ab72f5e1e8547c014c564"},{"url":"https://git.kernel.org/stable/c/5ac38f4b4862fad6e7270fde5c3356a822ce74ca"},{"url":"https://git.kernel.org/stable/c/f11deb032fd84081e7831cffcba895d893054a22"}],"title":"dm-pcache: validate kset key_num and intra-segment bounds","x_generator":{"engine":"bippy-1.2.0"}}}}