{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80959","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-08-26T14:34:25.809Z","datePublished":"2026-09-11T19:42:26.514Z","dateUpdated":"2026-09-13T06:28:31.649Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-13T06:28:31.649Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ndm-pcache: bound the persisted tail-position offset\n\ncache_pos_decode() takes the persisted key_tail and dirty_tail seg_off from\nthe cache device and addresses within the segment with it. A seg_off at or\npast the segment data_size, controllable by whoever supplies the device\n(CAP_SYS_ADMIN), reads past the segment data.\n\nReject a decoded seg_off that is not below the segment data_size."}],"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 unbounded tail offset is consumed only when a local caller loads a dm-pcache table (ctl_ioctl → table_load → dm_pcache_ctr → pcache_cache_start → cache_tail_init → cache_pos_decode) from a supplied DAX cache device; no network, Bluetooth, or USB receive path parses this metadata.\nAC:L - The attacker fully controls the cache device and can forge key_tail/dirty_tail pos_onmedia with a valid CRC (public PCACHE_CRC_SEED), so cache_pos_decode() deterministically accepts an out-of-range seg_off; no race or uninfluenced victim state is required.\nPR:L - dm-ioctl.c gates table load with capable(CAP_SYS_ADMIN); kernel-CNA scoring treats that delegated capability (privileged containers, LVM/storage helpers) as Low rather than exclusive init-namespace root, and the attacker supplies the cache/backing devices on the pcache table.\nUI:N - The attacker performs every step itself: craft the persisted tail positions on a DAX cache device and issue DM_TABLE_LOAD for a pcache target; no other user must mount media, open files, or otherwise interact.\nS:U - The out-of-bounds pmem/kernel access and resulting oops stay inside the host kernel device-mapper/pcache mapping; this is not a VM escape, IOMMU bypass, or other cross-authority boundary.\nC:H - cache_replay(), writeback and GC copy ksets via copy_mc_to_kernel from cache_pos_addr() (segment.data plus the attacker-controlled u32 seg_off) for up to PCACHE_KSET_ONMEDIA_SIZE_MAX bytes, an unbounded over-read past segment data into later pmem or adjacent kernel VA, not a few-byte leak.\nI:H - A seg_off at data_size makes append_last_kset() memcpy_flushcache a kset into the next 16MiB segment's control metadata; a larger seg_off underflows u32 cache_seg_remain() so later key-head writes become arbitrary-offset stores through the DAX mapping, an out-of-bounds write primitive.\nA:H - cache_pos_advance() hits BUG_ON(cache_seg_remain(pos) < len) when a tail sits at data_size, and a huge seg_off makes copy_mc_to_kernel/memcpy_flushcache walk off the DAX mapping into unmapped kernel VA, oopsing or panicking the host."}]}],"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.c"],"versions":[{"version":"1d57628ff95b32d5cfa8d8f50e07690c161e9cf0","lessThan":"ffd9a214a94f9928e54856f42b1cc3e33fb10e36","status":"affected","versionType":"git"},{"version":"1d57628ff95b32d5cfa8d8f50e07690c161e9cf0","lessThan":"8bf7a06ca3c1611809725f58cfd573f2ffbda75f","status":"affected","versionType":"git"},{"version":"1d57628ff95b32d5cfa8d8f50e07690c161e9cf0","lessThan":"d1898576090a10d2ac2715218a652e78fb65a6b0","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.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/ffd9a214a94f9928e54856f42b1cc3e33fb10e36"},{"url":"https://git.kernel.org/stable/c/8bf7a06ca3c1611809725f58cfd573f2ffbda75f"},{"url":"https://git.kernel.org/stable/c/d1898576090a10d2ac2715218a652e78fb65a6b0"}],"title":"dm-pcache: bound the persisted tail-position offset","x_generator":{"engine":"bippy-1.2.0"}}}}