GHSA-JVQW-3P6Q-2FGX
Vulnerability from github – Published: 2026-09-17 18:31 – Updated: 2026-09-18 18:31In 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.
{
"affected": [],
"aliases": [
"CVE-2026-90246"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:17:20Z",
"severity": "HIGH"
},
"details": "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.",
"id": "GHSA-jvqw-3p6q-2fgx",
"modified": "2026-09-18T18:31:28Z",
"published": "2026-09-17T18:31:57Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90246"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/465946d3c560c0137e6a180ba054dddc4d049f5a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ef79a405f83993f0fda5efde371d98433f7d7a47"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- 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.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- 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.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Related by attack behaviour
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.