{ "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": "2026-10-19T08:45:43.213Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:45:43.213Z" }, "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", "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/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" } } } }