{"id":"CVE-2026-90246","summary":"apparmor: fix integer overflow in verify_tags() bounds check","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'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 \u003c sets.size guarantee.","modified":"2026-09-18T03:48:36.509790546Z","published":"2026-09-17T16:07:48.524Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90246.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/465946d3c560c0137e6a180ba054dddc4d049f5a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ef79a405f83993f0fda5efde371d98433f7d7a47"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90246.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90246"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3d28e2397af7a89ac3de33c686ed404cda59b5d5"},{"fixed":"ef79a405f83993f0fda5efde371d98433f7d7a47"},{"fixed":"465946d3c560c0137e6a180ba054dddc4d049f5a"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90246.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"7.0.0"},{"fixed":"7.2.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90246.json"}}],"schema_version":"1.9.0"}