{"id":"CVE-2025-21966","state":"PUBLISHED","title":"dm-flakey: Fix memory corruption in optional corrupt_bio_byte feature","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ndm-flakey: Fix memory corruption in optional corrupt_bio_byte feature\n\nFix memory corruption due to incorrect parameter being passed to bio_init","publishedAt":"2025-04-01T15:47:01.836Z","updatedAt":"2026-08-05T11:55:42.212Z","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":"1d9a943898533e83f20370c0e1448d606627522e","status":"affected","lessThan":"818330f756f3800c37d738bd36bce60eac949938","versionType":"git"},{"version":"1d9a943898533e83f20370c0e1448d606627522e","status":"affected","lessThan":"5a87e46da2418c57b445371f5ca0958d5779ba5f","versionType":"git"},{"version":"1d9a943898533e83f20370c0e1448d606627522e","status":"affected","lessThan":"da070843e153471be4297a12fdaa64023276f40e","versionType":"git"},{"version":"1d9a943898533e83f20370c0e1448d606627522e","status":"affected","lessThan":"57e9417f69839cb10f7ffca684c38acd28ceb57b","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/dm-flakey.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.5","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.5","versionType":"semver"},{"version":"6.6.84","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.20","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.13.8","status":"unaffected","lessThanOrEqual":"6.13.*","versionType":"semver"},{"version":"6.14","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-flakey.c"]}],"references":["https://git.kernel.org/stable/c/818330f756f3800c37d738bd36bce60eac949938","https://git.kernel.org/stable/c/5a87e46da2418c57b445371f5ca0958d5779ba5f","https://git.kernel.org/stable/c/da070843e153471be4297a12fdaa64023276f40e","https://git.kernel.org/stable/c/57e9417f69839cb10f7ffca684c38acd28ceb57b"],"weaknesses":["CWE-787"],"ingestedAt":"2026-10-29T20:08:39.238Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/21xxx/CVE-2025-21966.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-21966","state":"PUBLISHED","datePublished":"2025-04-01T15:47:01.836Z","dateUpdated":"2026-08-05T11:55:42.212Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-12-29T08:45:45.796Z"},"containers":{"cna":{"title":"dm-flakey: Fix memory corruption in optional corrupt_bio_byte feature","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ndm-flakey: Fix memory corruption in optional corrupt_bio_byte feature\n\nFix memory corruption due to incorrect parameter being passed to bio_init"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1d9a943898533e83f20370c0e1448d606627522e","status":"affected","lessThan":"818330f756f3800c37d738bd36bce60eac949938","versionType":"git"},{"version":"1d9a943898533e83f20370c0e1448d606627522e","status":"affected","lessThan":"5a87e46da2418c57b445371f5ca0958d5779ba5f","versionType":"git"},{"version":"1d9a943898533e83f20370c0e1448d606627522e","status":"affected","lessThan":"da070843e153471be4297a12fdaa64023276f40e","versionType":"git"},{"version":"1d9a943898533e83f20370c0e1448d606627522e","status":"affected","lessThan":"57e9417f69839cb10f7ffca684c38acd28ceb57b","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/dm-flakey.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.5","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.5","versionType":"semver"},{"version":"6.6.84","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.20","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.13.8","status":"unaffected","lessThanOrEqual":"6.13.*","versionType":"semver"},{"version":"6.14","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-flakey.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/818330f756f3800c37d738bd36bce60eac949938"},{"url":"https://git.kernel.org/stable/c/5a87e46da2418c57b445371f5ca0958d5779ba5f"},{"url":"https://git.kernel.org/stable/c/da070843e153471be4297a12fdaa64023276f40e"},{"url":"https://git.kernel.org/stable/c/57e9417f69839cb10f7ffca684c38acd28ceb57b"}],"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 corruption is triggered by write I/O submitted locally to a dm-flakey block device or a filesystem mounted on it; there is no remote or network-facing path into drivers/md/dm-flakey.c.\nAC:L - Once the target is configured, every matching write bio during the down interval deterministically overflows the neighbouring slab object — no race to win and the up/down cycle is periodic and predictable, so the attacker simply writes or retries.\nPR:L - Creating the dm-flakey table needs CAP_SYS_ADMIN, but on the systems where this feature is actually deployed (fstests/CI/QA fault-injection hosts) any unprivileged user with write access to the device or its mounted filesystem triggers the out-of-bounds write with ordinary writes.\nUI:N - The attacker's own writes drive the corruption; no action by another user or administrator is needed beyond the pre-existing device configuration.\nS:U - The out-of-bounds write corrupts kernel slab memory within the same kernel security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The clone's bvec array aliases memory outside the original bio's allocation, and the subsequent `bio_for_each_folio_all()`/`folio_put()` walk reads back whatever now occupies that neighbouring live object, giving a controlled heap corruption primitive usable for arbitrary kernel memory disclosure.\nI:H - This is a direct heap out-of-bounds write of `struct bio_vec` records (page pointer, length, offset) into adjacent slab objects — from 16 bytes up to ~16 KB under attacker-inducible allocation-order fallback — a classic exploitable primitive for pointer corruption and control-flow hijack.\nA:H - Corrupting adjacent `dm_io`/`dm_target_io`/bio structures and calling `folio_put()` on garbage pointers reliably produces oopses, BUG_ONs, and page refcount corruption leading to kernel panic."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T11:55:42.212Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.5","versionEndExcluding":"6.6.84"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.5","versionEndExcluding":"6.12.20"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.5","versionEndExcluding":"6.13.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.5","versionEndExcluding":"6.14"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":7.8,"attackVector":"LOCAL","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","integrityImpact":"HIGH","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"LOW","confidentialityImpact":"HIGH"}},{"other":{"type":"ssvc","content":{"timestamp":"2025-10-01T18:16:20.613850Z","id":"CVE-2025-21966","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-787","type":"CWE","lang":"en","description":"CWE-787 Out-of-bounds Write"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2025-10-01T18:16:24.672Z"}}]}}}