{"id":"CVE-2026-89761","title":"apparmor: fix out-of-bounds write when null terminating a label vec","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\napparmor: fix out-of-bounds write when null terminating a label vec\n\naa_vec_unique() null terminates at vec[n - dups] when VEC_FLAG_TERMINATE\nis passed. If the componen…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","cwe":["CWE-787"],"vendor":"Linux","product":"Linux","affected":["Linux >= f1bd904175e8190ce14aedee37e207ab51fe3b30 < b17c8f5dcb36a032688847b2bce4bd813b4baad1","Linux >= f1bd904175e8190ce14aedee37e207ab51fe3b30 < 9124e078ea2250d8d01d2162a550acb01ef5bf48","Linux >= f1bd904175e8190ce14aedee37e207ab51fe3b30 < 28069434aef66b9d084f0609b7a29c171846815e","Linux >= f1bd904175e8190ce14aedee37e207ab51fe3b30 < 36bdd0b45ec3f4822832a56e9db8674c8450dfce","Linux >= f1bd904175e8190ce14aedee37e207ab51fe3b30 < 9f1e40193eef7f047e6b77cfb4b4cafdecd7a123","Linux 4.13"],"published":"2026-09-11","updated":"2026-10-21","sourceUpdated":"2026-10-21T12:48:38.023Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89761","references":[{"url":"https://git.kernel.org/stable/c/b17c8f5dcb36a032688847b2bce4bd813b4baad1"},{"url":"https://git.kernel.org/stable/c/9124e078ea2250d8d01d2162a550acb01ef5bf48"},{"url":"https://git.kernel.org/stable/c/28069434aef66b9d084f0609b7a29c171846815e"},{"url":"https://git.kernel.org/stable/c/36bdd0b45ec3f4822832a56e9db8674c8450dfce"},{"url":"https://git.kernel.org/stable/c/9f1e40193eef7f047e6b77cfb4b4cafdecd7a123"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89761.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89761"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532235"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89761"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89761"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89761.mbox"}],"tags":["cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.0012,"epssPercentile":0.01832,"scores":{"cna":7.8,"vendor":5.5},"ingestedAt":"2026-09-14T15:23:07.472Z","slug":"CVE-2026-89761","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\napparmor: fix out-of-bounds write when null terminating a label vec\n\naa_vec_unique() null terminates at vec[n - dups] when VEC_FLAG_TERMINATE\nis passed. If the components are all distinct no duplicates are dropped,\ndups is 0 and the terminator goes to vec[n], so the caller has to provide\nroom for n + 1 entries.\n\naa_label_strn_parse() sets up its vector with vec_setup(profile, vec, len,\ngfp) and then calls aa_vec_unique(vec, len, VEC_FLAG_TERMINATE), but\nvec_setup() does not reserve the terminator entry. Up to LOCAL_VEC_ENTRIES\nit uses the local array of LOCAL_VEC_ENTRIES pointers, above that it\nallocates exactly len pointers. The terminator therefore lands one entry\npast the end of the local array when len is LOCAL_VEC_ENTRIES, and one\nentry past the end of the allocation when len is larger.\n\nlen comes from the number of \"//&\" separated components in the label name\nand label_count_strn_entries() does not bound it. An unprivileged task\nreaches the parse by writing to /proc/self/attr/apparmor/current or through\nlsm_set_self_attr(2), both of which go through do_setattr(), and the name\nis parsed before the change_profile permission is checked.\nThe query_label() path behind the securityfs .access file, which is\nmode 0666, performs no permission check at all. Every component has to\nresolve to a loaded profile, so a system with policy loaded is required.\n\nThe other two VEC_FLAG_TERMINATE users work on a label vec that\naa_label_alloc() has already sized with \"+ 1 for null terminator entry on\nvec\". Reserve the same entry in vec_setup() and DEFINE_VEC(). Passing\nlen + 1 from the caller instead would move len == LOCAL_VEC_ENTRIES out of\nthe local array and into kzalloc().\n\n## Affected\n\n- `Linux >= f1bd904175e8190ce14aedee37e207ab51fe3b30 < b17c8f5dcb36a032688847b2bce4bd813b4baad1`\n- `Linux >= f1bd904175e8190ce14aedee37e207ab51fe3b30 < 9124e078ea2250d8d01d2162a550acb01ef5bf48`\n- `Linux >= f1bd904175e8190ce14aedee37e207ab51fe3b30 < 28069434aef66b9d084f0609b7a29c171846815e`\n- `Linux >= f1bd904175e8190ce14aedee37e207ab51fe3b30 < 36bdd0b45ec3f4822832a56e9db8674c8450dfce`\n- `Linux >= f1bd904175e8190ce14aedee37e207ab51fe3b30 < 9f1e40193eef7f047e6b77cfb4b4cafdecd7a123`\n- `Linux 4.13`\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 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89761.json)","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":224568,"id":"CVE-2026-89761","ts":1792401412198,"field":"cvss","old":"5.5","new":"7.8"},{"seq":224567,"id":"CVE-2026-89761","ts":1792401412198,"field":"severity","old":"medium","new":"high"},{"seq":208936,"id":"CVE-2026-89761","ts":1790062294221,"field":"cvss","old":"7.8","new":"5.5"},{"seq":208935,"id":"CVE-2026-89761","ts":1790062294221,"field":"severity","old":"high","new":"medium"},{"seq":197664,"id":"CVE-2026-89761","ts":1789384318305,"field":"cvss","old":"6.5","new":"7.8"},{"seq":197663,"id":"CVE-2026-89761","ts":1789384318305,"field":"severity","old":"medium","new":"high"},{"seq":183845,"id":"CVE-2026-89761","ts":1789356677646,"field":"cvss","old":"7.8","new":"6.5"},{"seq":183844,"id":"CVE-2026-89761","ts":1789356677646,"field":"severity","old":"high","new":"medium"},{"seq":153648,"id":"CVE-2026-89761","ts":1789285351715,"field":"cvss","old":null,"new":"7.8"},{"seq":153647,"id":"CVE-2026-89761","ts":1789285351715,"field":"severity","old":"none","new":"high"},{"seq":147578,"id":"CVE-2026-89761","ts":1789270211459,"field":"cvss","old":null,"new":"6.5"},{"seq":147577,"id":"CVE-2026-89761","ts":1789270211459,"field":"severity","old":"none","new":"medium"},{"seq":109336,"id":"CVE-2026-89761","ts":1789183731476,"field":"cvss","old":null,"new":"6.5"},{"seq":109335,"id":"CVE-2026-89761","ts":1789183731476,"field":"severity","old":"none","new":"medium"}]}