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CVE-2026-89761 (GCVE-0-2026-89761)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:47 – Updated: 2026-09-13 06:34
VLAI
Title
apparmor: fix out-of-bounds write when null terminating a label vec
Summary
In the Linux kernel, the following vulnerability has been resolved: apparmor: fix out-of-bounds write when null terminating a label vec aa_vec_unique() null terminates at vec[n - dups] when VEC_FLAG_TERMINATE is passed. If the components are all distinct no duplicates are dropped, dups is 0 and the terminator goes to vec[n], so the caller has to provide room for n + 1 entries. aa_label_strn_parse() sets up its vector with vec_setup(profile, vec, len, gfp) and then calls aa_vec_unique(vec, len, VEC_FLAG_TERMINATE), but vec_setup() does not reserve the terminator entry. Up to LOCAL_VEC_ENTRIES it uses the local array of LOCAL_VEC_ENTRIES pointers, above that it allocates exactly len pointers. The terminator therefore lands one entry past the end of the local array when len is LOCAL_VEC_ENTRIES, and one entry past the end of the allocation when len is larger. len comes from the number of "//&" separated components in the label name and label_count_strn_entries() does not bound it. An unprivileged task reaches the parse by writing to /proc/self/attr/apparmor/current or through lsm_set_self_attr(2), both of which go through do_setattr(), and the name is parsed before the change_profile permission is checked. The query_label() path behind the securityfs .access file, which is mode 0666, performs no permission check at all. Every component has to resolve to a loaded profile, so a system with policy loaded is required. The other two VEC_FLAG_TERMINATE users work on a label vec that aa_label_alloc() has already sized with "+ 1 for null terminator entry on vec". Reserve the same entry in vec_setup() and DEFINE_VEC(). Passing len + 1 from the caller instead would move len == LOCAL_VEC_ENTRIES out of the local array and into kzalloc().
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: f1bd904175e8190ce14aedee37e207ab51fe3b30 , < 9124e078ea2250d8d01d2162a550acb01ef5bf48 (git)
Affected: f1bd904175e8190ce14aedee37e207ab51fe3b30 , < 28069434aef66b9d084f0609b7a29c171846815e (git)
Affected: f1bd904175e8190ce14aedee37e207ab51fe3b30 , < 36bdd0b45ec3f4822832a56e9db8674c8450dfce (git)
Affected: f1bd904175e8190ce14aedee37e207ab51fe3b30 , < 9f1e40193eef7f047e6b77cfb4b4cafdecd7a123 (git)
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Linux Linux Affected: 4.13
Unaffected: 0 , < 4.13 (semver)
Unaffected: 6.12.109 , ≤ 6.12.* (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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          "product": "Linux",
          "programFiles": [
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          "lang": "en",
          "value": "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 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 \"//\u0026\" 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()."
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            "baseSeverity": "HIGH",
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            "version": "3.1"
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              "value": "AV:L - An unprivileged local process reaches aa_label_strn_parse() by writing a compound label to /sys/kernel/security/apparmor/.access (mode 0666) via query_label()/query_data(), or via /proc/self/attr/apparmor/current and lsm_set_self_attr(2) through do_setattr(); there is no network-facing path.\nAC:L - The attacker fully controls the \"//\u0026\"-separated label string and thus the vector length; when at least eight distinct profiles are loaded (typical Ubuntu/Debian/SUSE policy, or attacker-loaded via user namespaces) with no duplicates, aa_vec_unique() deterministically writes NULL one pointer past the stack array or heap allocation, with no race.\nPR:L - query_label() on the world-writable .access file performs no capability or change_profile check, and do_setattr() parses the name before AA_MAY_CHANGE_PROFILE is tested, so a basic unprivileged local user suffices; real root is not required.\nUI:N - The attacker opens and writes the .access query or their own procattr themselves; no victim action such as mounting a filesystem or opening a file is required.\nS:U - The out-of-bounds write corrupts kernel stack or heap within the same kernel security authority. This is standard local privilege-escalation impact, not a VM escape or IOMMU/sandbox boundary crossing.\nC:H - The one-pointer out-of-bounds write lands in adjacent stack locals or the next kmalloc object. With attacker-chosen allocation size (component count) for heap grooming, that corruption can be leveraged as a kernel memory-disclosure primitive, so confidentiality impact is high.\nI:H - aa_vec_unique() writes a NULL pointer one slot past a LOCAL_VEC_ENTRIES stack array or a heap buffer sized exactly to the attacker-chosen component count. An out-of-bounds write that corrupts adjacent kernel objects is a write primitive suitable for control-flow hijacking.\nA:H - Corrupting an adjacent stack pointer, heap object, or stack canary can oops, panic, or hang the kernel; the unexploited NULL write alone is sufficient for denial of service."
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/36bdd0b45ec3f4822832a56e9db8674c8450dfce"
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          "url": "https://git.kernel.org/stable/c/9f1e40193eef7f047e6b77cfb4b4cafdecd7a123"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89761",
    "datePublished": "2026-09-11T19:47:02.837Z",
    "dateReserved": "2026-09-11T19:38:34.764Z",
    "dateUpdated": "2026-09-13T06:34:05.104Z",
    "state": "PUBLISHED"
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      "date": "2026-09-16",
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Passing\\nlen + 1 from the caller instead would move len == LOCAL_VEC_ENTRIES out of\\nthe local array and into kzalloc().\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"security/apparmor/include/label.h\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"f1bd904175e8190ce14aedee37e207ab51fe3b30\",\"lessThan\":\"9124e078ea2250d8d01d2162a550acb01ef5bf48\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"f1bd904175e8190ce14aedee37e207ab51fe3b30\",\"lessThan\":\"28069434aef66b9d084f0609b7a29c171846815e\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"f1bd904175e8190ce14aedee37e207ab51fe3b30\",\"lessThan\":\"36bdd0b45ec3f4822832a56e9db8674c8450dfce\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"f1bd904175e8190ce14aedee37e207ab51fe3b30\",\"lessThan\":\"9f1e40193eef7f047e6b77cfb4b4cafdecd7a123\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"security/apparmor/include/label.h\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"4.13\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"4.13\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.109\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.50\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2.4\",\"lessThanOrEqual\":\"7.2.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.3-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"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\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/28069434aef66b9d084f0609b7a29c171846815e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/36bdd0b45ec3f4822832a56e9db8674c8450dfce\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9124e078ea2250d8d01d2162a550acb01ef5bf48\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9f1e40193eef7f047e6b77cfb4b4cafdecd7a123\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-09-13T06:47:28+00:00",
      "cve": "CVE-2026-89761",
      "id": "CVE-2026-89761",
      "initial_release_date": "2026-09-11T19:47:02.837000+00:00",
      "product_status:known_affected": "2",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Kernel: AppArmor out-of-bounds write allows local denial of service or privilege escalation",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89761.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.