{ "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": "2026-10-19T08:45:45.271Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:45:45.271Z" }, "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", "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/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" } } } }