{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-90246", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.795Z", "datePublished": "2026-09-17T16:07:48.524Z", "dateUpdated": "2026-10-19T09:00:22.097Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:00:22.097Z" }, "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->sets.table[i];\n\n\tif (i+cnt >= tags->sets.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 >= 2 is false, inner loop does not run\n i = 1: cnt = 0xffffffff, guard (1 + 0xffffffff) mod 2^32 == 0 >= 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 >=\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 -> aa_unpack -> unpack_policydb -> unpack_tags ->\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's 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 < sets.size guarantee." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "baseScore": 7.1, "baseSeverity": "HIGH" }, "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 → policy_update → aa_replace_profiles → aa_unpack → unpack_profile → unpack_pdb → unpack_tags → unpack_tagsets → 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->user_ns, not init_user_ns. With default unprivileged_userns_apparmor_policy=1, aa_policy_view_capable() permits a uid-0 task whose user_ns->level equals labels_view(label)->level, 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->sets.table[++i] for cnt near U32_MAX, walking u32s past the kcalloc(size,sizeof(u32)) allocation until a value is >= 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 >= hdrs.size, i wraps and the outer for (i < sets.size) loop in verify_tags() never terminates, hanging the policy-load task." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "security/apparmor/policy_unpack.c" ], "versions": [ { "version": "3d28e2397af7a89ac3de33c686ed404cda59b5d5", "lessThan": "ef79a405f83993f0fda5efde371d98433f7d7a47", "status": "affected", "versionType": "git" }, { "version": "3d28e2397af7a89ac3de33c686ed404cda59b5d5", "lessThan": "465946d3c560c0137e6a180ba054dddc4d049f5a", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "security/apparmor/policy_unpack.c" ], "versions": [ { "version": "7.0", "status": "affected" }, { "version": "0", "lessThan": "7.0", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.6", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.0", "versionEndExcluding": "7.2.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.0", "versionEndExcluding": "7.3" } ] } ] } ], "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" } } } }