CVE-2026-90246 (GCVE-0-2026-90246)
Vulnerability from cvelistv5
Published
2026-09-17 16:07
Modified
2026-10-19 09:00
Severity ?
7.1 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: apparmor: fix integer overflow in verify_tags() bounds check verify_tags() validates the tagset table unpacked from a policy blob. For each set it reads a count and checks that advancing the index by that count stays inside sets.table[]: u32 cnt = tags->sets.table[i]; if (i+cnt >= tags->sets.size) { i, cnt and sets.size are all u32, so i+cnt is evaluated modulo 2^32. sets.table[] is filled by unpack_tagsets() with aa_unpack_u32(), so every entry is a raw unbounded 32-bit word taken from the policy blob, and verify_tags() is the function that is supposed to validate it. A count close to U32_MAX makes the sum wrap to a small value, the guard passes, and the inner loop then walks sets.table[++i] past the end of the kcalloc(size, sizeof(u32)) allocation. Note that sets.size is bounded by 65535, because unpack_tagsets() reads it with aa_unpack_array() as a u16, so the wrap cannot be reached by growing the table; it is reached purely through the attacker-supplied count. With sets.size = 2 and sets.table = { 0, 0xffffffff }: i = 0: cnt = 0, guard 0 + 0 >= 2 is false, inner loop does not run i = 1: cnt = 0xffffffff, guard (1 + 0xffffffff) mod 2^32 == 0 >= 2 is false, so the guard is bypassed and the inner loop reads sets.table[2] -- one element past a two element allocation The walk continues until an out-of-bounds value happens to be >= hdrs.size or the access faults, so a crafted policy yields an out-of-bounds read on the policy load path (aa_replace_profiles -> aa_unpack -> unpack_policydb -> unpack_tags -> verify_tags). unpack_tags() runs before the perms and DFA tables are unpacked, so no other table needs to be well formed to reach it. Policy load is gated by aa_may_manage_policy(), which checks CAP_MAC_ADMIN relative to the subject's own user namespace rather than the init user namespace, so with the default unprivileged_userns_apparmor_policy=1 the path is reachable from an unprivileged task in a matched-level nested namespace, not only by a globally privileged one. Perform the addition in u64 so that it cannot wrap, restoring the intended i + cnt < sets.size guarantee.
References
Impacted products
Vendor Product Version
Linux Linux Version: 3d28e2397af7a89ac3de33c686ed404cda59b5d5
Version: 3d28e2397af7a89ac3de33c686ed404cda59b5d5
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "security/apparmor/policy_unpack.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "ef79a405f83993f0fda5efde371d98433f7d7a47",
              "status": "affected",
              "version": "3d28e2397af7a89ac3de33c686ed404cda59b5d5",
              "versionType": "git"
            },
            {
              "lessThan": "465946d3c560c0137e6a180ba054dddc4d049f5a",
              "status": "affected",
              "version": "3d28e2397af7a89ac3de33c686ed404cda59b5d5",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "security/apparmor/policy_unpack.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "lessThan": "7.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.6",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\napparmor: fix integer overflow in verify_tags() bounds check\n\nverify_tags() validates the tagset table unpacked from a policy blob.\nFor each set it reads a count and checks that advancing the index by\nthat count stays inside sets.table[]:\n\n\tu32 cnt = tags-\u003esets.table[i];\n\n\tif (i+cnt \u003e= tags-\u003esets.size) {\n\ni, cnt and sets.size are all u32, so i+cnt is evaluated modulo 2^32.\nsets.table[] is filled by unpack_tagsets() with aa_unpack_u32(), so\nevery entry is a raw unbounded 32-bit word taken from the policy blob,\nand verify_tags() is the function that is supposed to validate it.  A\ncount close to U32_MAX makes the sum wrap to a small value, the guard\npasses, and the inner loop then walks sets.table[++i] past the end of\nthe kcalloc(size, sizeof(u32)) allocation.\n\nNote that sets.size is bounded by 65535, because unpack_tagsets() reads\nit with aa_unpack_array() as a u16, so the wrap cannot be reached by\ngrowing the table; it is reached purely through the attacker-supplied\ncount.\n\nWith sets.size = 2 and sets.table = { 0, 0xffffffff }:\n\n  i = 0: cnt = 0, guard 0 + 0 \u003e= 2 is false, inner loop does not run\n  i = 1: cnt = 0xffffffff, guard (1 + 0xffffffff) mod 2^32 == 0 \u003e= 2 is\n         false, so the guard is bypassed and the inner loop reads\n         sets.table[2] -- one element past a two element allocation\n\nThe walk continues until an out-of-bounds value happens to be \u003e=\nhdrs.size or the access faults, so a crafted policy yields an\nout-of-bounds read on the policy load path\n(aa_replace_profiles -\u003e aa_unpack -\u003e unpack_policydb -\u003e unpack_tags -\u003e\nverify_tags).  unpack_tags() runs before the perms and DFA tables are\nunpacked, so no other table needs to be well formed to reach it.\n\nPolicy load is gated by aa_may_manage_policy(), which checks\nCAP_MAC_ADMIN relative to the subject\u0027s own user namespace rather than\nthe init user namespace, so with the default\nunprivileged_userns_apparmor_policy=1 the path is reachable from an\nunprivileged task in a matched-level nested namespace, not only by a\nglobally privileged one.\n\nPerform the addition in u64 so that it cannot wrap, restoring the\nintended i + cnt \u003c sets.size guarantee."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The overflowing tagset count is a u32 in the policy blob the attacker write()s to /sys/kernel/security/apparmor/.load or .replace (profile_load/profile_replace \u2192 policy_update \u2192 aa_replace_profiles \u2192 aa_unpack \u2192 unpack_profile \u2192 unpack_pdb \u2192 unpack_tags \u2192 unpack_tagsets \u2192 verify_tags). The malformed word does not arrive in a network protocol message.\nAC:L - unpack_tagsets() stores attacker-chosen u32s from aa_unpack_u32() into sets.table[]; with sets.size=2 and table {0,0xffffffff}, i+cnt wraps modulo 2^32 to 0 so the bounds guard is skipped every time. No race or victim-side state is required.\nPR:L - policy_update() calls aa_may_manage_policy(), which checks CAP_MAC_ADMIN via policy_ns_capable() against subj_cred-\u003euser_ns, not init_user_ns. With default unprivileged_userns_apparmor_policy=1, aa_policy_view_capable() permits a uid-0 task whose user_ns-\u003elevel equals labels_view(label)-\u003elevel, so unprivileged nested-namespace (container) root can load the crafted blob.\nUI:N - The attacker supplies the packed profile with a tags.sets count of 0xffffffff through their own write to .load/.replace; no other user must mount a volume, open a file, or load policy on their behalf.\nS:U - The OOB read is of the kernel slab object allocated by kcalloc() in unpack_tagsets() while unpacking policy in the host kernel; it does not cross a VM, IOMMU, or other security-authority boundary.\nC:H - After the wrap, verify_tags() executes tags-\u003esets.table[++i] for cnt near U32_MAX, walking u32s past the kcalloc(size,sizeof(u32)) allocation until a value is \u003e= hdrs.size or the access faults. That over-read is not limited to a few bytes.\nI:N - The overflowing loop only reads sets.table[++i] and compares it to hdrs.size; it performs no store through the overflowing index, and aa_unpack() never installs the profile if verify_tags() returns false, oopses, or spins.\nA:H - cnt near U32_MAX causes ~2^32 OOB reads from the sets.table slab object, which oopses when the walk hits unmapped pages; if no OOB word is \u003e= hdrs.size, i wraps and the outer for (i \u003c sets.size) loop in verify_tags() never terminates, hanging the policy-load task."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:00:22.097Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/ef79a405f83993f0fda5efde371d98433f7d7a47"
        },
        {
          "url": "https://git.kernel.org/stable/c/465946d3c560c0137e6a180ba054dddc4d049f5a"
        }
      ],
      "title": "apparmor: fix integer overflow in verify_tags() bounds check",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90246",
    "datePublished": "2026-09-17T16:07:48.524Z",
    "dateReserved": "2026-09-11T19:38:34.795Z",
    "dateUpdated": "2026-10-19T09:00:22.097Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.