{"id":"CVE-2026-80956","title":"dm-pcache: only hand out initialized cache segments","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ndm-pcache: only hand out initialized cache segments\n\nget_cache_segment() scans the segment map up to cache->n_segs, the\nphysical device segment count, but cache_segs_in…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":["CWE-824"],"vendor":"Linux","product":"Linux","affected":["Linux >= 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 < 83e3116283ed2c6a6a1fa662862a4b4d7d2701a2","Linux >= 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 < 692037ae1a7cfacc2f0c22c6e034c1dfee0e553f","Linux >= 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 < 2df0fc042e299bae3c0f60ea5cd2af9285658e9f","Linux 6.18"],"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:45:40.093Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-80956","references":[{"url":"https://git.kernel.org/stable/c/83e3116283ed2c6a6a1fa662862a4b4d7d2701a2"},{"url":"https://git.kernel.org/stable/c/692037ae1a7cfacc2f0c22c6e034c1dfee0e553f"},{"url":"https://git.kernel.org/stable/c/2df0fc042e299bae3c0f60ea5cd2af9285658e9f"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80956.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-80956"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532400"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-80956"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80956"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-80956.mbox"}],"tags":["cve.org","csaf","vex","red-hat"],"epss":0.00206,"epssPercentile":0.10629,"ingestedAt":"2026-09-14T00:35:28.532Z","slug":"CVE-2026-80956","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ndm-pcache: only hand out initialized cache segments\n\nget_cache_segment() scans the segment map up to cache->n_segs, the\nphysical device segment count, but cache_segs_init() only initializes\nthe first cache_info->n_segs segments. A crafted image with\ncache_info->n_segs smaller than the device count leaves the remaining\npcache_cache_segment structs zeroed (segment.data == NULL), and the\nallocator can hand one to cache_kset_close(), which writes through the\nreturned segment's data pointer with no NULL check.\n\nBound the allocator's search to cache_info->n_segs so only initialized\nsegments are ever returned. A conforming cache sets n_segs equal to the\ndevice segment count, so this rejects nothing legitimate.\n\n## Affected\n\n- `Linux >= 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 < 83e3116283ed2c6a6a1fa662862a4b4d7d2701a2`\n- `Linux >= 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 < 692037ae1a7cfacc2f0c22c6e034c1dfee0e553f`\n- `Linux >= 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 < 2df0fc042e299bae3c0f60ea5cd2af9285658e9f`\n- `Linux 6.18`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80956.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":204239,"id":"CVE-2026-80956","ts":1789490240474,"field":"cvss","old":null,"new":"5.5"},{"seq":204238,"id":"CVE-2026-80956","ts":1789490240474,"field":"severity","old":"none","new":"medium"},{"seq":147287,"id":"CVE-2026-80956","ts":1789270207156,"field":"cvss","old":null,"new":"4.4"},{"seq":147286,"id":"CVE-2026-80956","ts":1789270207156,"field":"severity","old":"none","new":"medium"},{"seq":109046,"id":"CVE-2026-80956","ts":1789183730095,"field":"cvss","old":null,"new":"4.4"},{"seq":109045,"id":"CVE-2026-80956","ts":1789183730095,"field":"severity","old":"none","new":"medium"}]}