CVE-2026-89761

Estado: RecibidaAlta (7.8)—

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.

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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().

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.12%
Percentil entre todas las CVEs puntuadas: 2
Fecha de la puntuación: 5/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation95 %
Impacto principalT1059 Command and Scripting Interpreterexecution85 %
Impacto secundarioT1499.004 Application or System Exploitationimpact70 %

Vulnerabilidad de escritura fuera de límites (heap buffer overflow) en kernel Linux accesible por tareas sin privilegios vía /proc/self/attr/apparmor/current. AV:L, PR:L permite escalada de privilegios (T1068) con ejecución de código (T1059) o negación de servicio (T1499.004) por corrupción de memor

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Execution Prevention Threat Intelligence Program Restrict Web-Based Content Privileged Account Management Limit Software Installation Filter Network Traffic

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Linux — Linux Kernel^AI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-89761",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "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"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 1.8
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "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"
            }
          ],
          "programFiles": [
            "security/apparmor/include/label.h"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.13"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "4.13",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "security/apparmor/include/label.h"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-11T20:20:07.243",
  "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"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "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 \"//&\" 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()."
    }
  ],
  "lastModified": "2026-09-13T07:17:40.427",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}