138 lines
9.6 KiB
JSON
138 lines
9.6 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-90246",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2026-09-11T19:38:34.795Z",
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"datePublished": "2026-09-17T16:07:48.524Z",
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"dateUpdated": "2026-10-19T09:00:22.097Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-10-19T09:00:22.097Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"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."
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
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"baseScore": 7.1,
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"baseSeverity": "HIGH"
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},
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"scenarios": [
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{
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"lang": "en",
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"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."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"security/apparmor/policy_unpack.c"
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],
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"versions": [
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{
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"version": "3d28e2397af7a89ac3de33c686ed404cda59b5d5",
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"lessThan": "ef79a405f83993f0fda5efde371d98433f7d7a47",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "3d28e2397af7a89ac3de33c686ed404cda59b5d5",
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"lessThan": "465946d3c560c0137e6a180ba054dddc4d049f5a",
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"status": "affected",
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"versionType": "git"
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"security/apparmor/policy_unpack.c"
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],
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"versions": [
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{
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"version": "7.0",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "7.0",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.2.6",
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"lessThanOrEqual": "7.2.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.3",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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{
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"nodes": [
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{
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "7.0",
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"versionEndExcluding": "7.2.6"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "7.0",
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"versionEndExcluding": "7.3"
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}
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]
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}
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]
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}
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/ef79a405f83993f0fda5efde371d98433f7d7a47"
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},
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{
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"url": "https://git.kernel.org/stable/c/465946d3c560c0137e6a180ba054dddc4d049f5a"
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}
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],
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"title": "apparmor: fix integer overflow in verify_tags() bounds check",
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"x_generator": {
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} |