{"id":"CVE-2026-80962","state":"PUBLISHED","title":"dm-pcache: validate geometry fields from on-disk cache_info","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ndm-pcache: validate geometry fields from on-disk cache_info\n\ncache_segs_init() iterates cache_info->n_segs times indexing\ncache->segments[], which is sized to the cache device geometry, and\nget_seg_id() takes each segment id from the on-media cache_info and the\nper-segment next_seg link. Both come from cache device metadata that is\nonly CRC-protected with a fixed public seed, so whoever supplies the\ncache device on a table load (CAP_SYS_ADMIN) controls them: an oversized\nn_segs or an out-of-range id drives an out-of-bounds access of\ncache->segments[] and a wild CACHE_DEV_SEGMENT() pointer into the device\nmapping -- an out-of-bounds read and write from on-disk data.\n\nReject an n_segs that exceeds the device segment count and a segment id\nthat is out of range before either is used. Valid metadata is unaffected.","publishedAt":"2026-09-11T19:42:28.500Z","updatedAt":"2026-10-19T08:45:46.216Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1d57628ff95b32d5cfa8d8f50e07690c161e9cf0","status":"affected","lessThan":"ab5dcde6fa96bc115b85f3621c60e39c66229a90","versionType":"git"},{"version":"1d57628ff95b32d5cfa8d8f50e07690c161e9cf0","status":"affected","lessThan":"3e19172089ec81132a8a48e802b1034a744209f4","versionType":"git"},{"version":"1d57628ff95b32d5cfa8d8f50e07690c161e9cf0","status":"affected","lessThan":"32d1809da31094ef76fd98dc1f1a8b55ca1295dd","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/dm-pcache/cache.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.18","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/dm-pcache/cache.c"]}],"references":["https://git.kernel.org/stable/c/ab5dcde6fa96bc115b85f3621c60e39c66229a90","https://git.kernel.org/stable/c/3e19172089ec81132a8a48e802b1034a744209f4","https://git.kernel.org/stable/c/32d1809da31094ef76fd98dc1f1a8b55ca1295dd"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:07.220Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/80xxx/CVE-2026-80962.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80962","state":"PUBLISHED","datePublished":"2026-09-11T19:42:28.500Z","dateUpdated":"2026-10-19T08:45:46.216Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-26T14:34:25.809Z"},"containers":{"cna":{"title":"dm-pcache: validate geometry fields from on-disk cache_info","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ndm-pcache: validate geometry fields from on-disk cache_info\n\ncache_segs_init() iterates cache_info->n_segs times indexing\ncache->segments[], which is sized to the cache device geometry, and\nget_seg_id() takes each segment id from the on-media cache_info and the\nper-segment next_seg link. Both come from cache device metadata that is\nonly CRC-protected with a fixed public seed, so whoever supplies the\ncache device on a table load (CAP_SYS_ADMIN) controls them: an oversized\nn_segs or an out-of-range id drives an out-of-bounds access of\ncache->segments[] and a wild CACHE_DEV_SEGMENT() pointer into the device\nmapping -- an out-of-bounds read and write from on-disk data.\n\nReject an n_segs that exceeds the device segment count and a segment id\nthat is out of range before either is used. Valid metadata is unaffected."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1d57628ff95b32d5cfa8d8f50e07690c161e9cf0","status":"affected","lessThan":"ab5dcde6fa96bc115b85f3621c60e39c66229a90","versionType":"git"},{"version":"1d57628ff95b32d5cfa8d8f50e07690c161e9cf0","status":"affected","lessThan":"3e19172089ec81132a8a48e802b1034a744209f4","versionType":"git"},{"version":"1d57628ff95b32d5cfa8d8f50e07690c161e9cf0","status":"affected","lessThan":"32d1809da31094ef76fd98dc1f1a8b55ca1295dd","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/dm-pcache/cache.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.18","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/dm-pcache/cache.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/ab5dcde6fa96bc115b85f3621c60e39c66229a90"},{"url":"https://git.kernel.org/stable/c/3e19172089ec81132a8a48e802b1034a744209f4"},{"url":"https://git.kernel.org/stable/c/32d1809da31094ef76fd98dc1f1a8b55ca1295dd"}],"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 OOB access is reached only through a local device-mapper table load on /dev/mapper/control (ctl_ioctl → table_load → populate_table → dm_pcache_ctr → pcache_start → pcache_cache_start → cache_segs_init/get_seg_id). No network, Bluetooth, or USB path feeds on-disk cache_info geometry.\nAC:L - The attacker fully controls on-media cache_info.n_segs, cache_info.seg_id and each segment next_seg, and can forge a passing CRC because PCACHE_CRC_SEED (0x3B15A) is public, so a crafted INIT_DONE image with oversized n_segs or out-of-range ids hits the OOB on every table load with no race.\nPR:L - ctl_ioctl gates DM_TABLE_LOAD with capable(CAP_SYS_ADMIN). In the most severe reasonable deployment that capability is held by a container or storage-stack administrator with delegated mapper and DAX/pmem nodes rather than exclusive host root, which kernel-CNA scoring of device-mapper table-load bugs maps to Low.\nUI:N - The attacker crafts the DAX cache-device metadata and issues DM_TABLE_LOAD themselves; no separate victim must mount a filesystem, open a file, or otherwise interact.\nS:U - Out-of-bounds indexing of cache->segments[] and wild CACHE_DEV_SEGMENT() pointers corrupt kernel memory on the same host that loaded the table. This stays within one kernel security authority and is not a VM escape or IOMMU bypass.\nC:H - An out-of-range seg_id makes CACHE_DEV_SEGMENT() point past the DAX mapping into kernel memory, and cache_seg_meta_load() copy_mc_to_kernel's that region; oversized n_segs also reads past the kvalloc'd segments[] array. That kernel memory-corruption read primitive is Confidentiality High.\nI:H - cache_seg_init() writes pcache_cache_segment fields past the kvalloc'd cache->segments[] when n_segs exceeds seg_num, and a wild CACHE_DEV_SEGMENT() is later written through memcpy_flushcache/memset. That out-of-bounds kernel write is Integrity High and exploitable for code execution.\nA:H - Heap overflow of cache->segments[] or dereference of a mapping-relative pointer past the DAX device causes a kernel oops or panic at table load, fully denying availability."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:45:46.216Z"},"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"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}