{"id":"CVE-2026-99040","state":"PUBLISHED","title":"KEYS: Fix add_key() race with keyring restriction","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKEYS: Fix add_key() race with keyring restriction\n\n__key_create_or_update() snapshots keyring->restrict_link before taking\nthe destination keyring's semaphore.  keyring_restrict() installs a\nrestriction while holding that semaphore.\n\nThis allows a writer to observe no restriction, wait for the keyring\nowner to install a reject-all restriction and return successfully, and\nthen link a key using the stale NULL snapshot.  The writer only needs\nwrite permission on the destination keyring.\n\nMove the restrict_link read after __key_link_lock() and\n__key_link_begin().  The read and the subsequent restriction check are\nthen serialized with restriction installation by keyring->sem.\n\nThe race was reproduced on v7.2.8 in 19 executions where restriction\ninstallation returned before the link completed.  All 19 linked the key\ndespite the reject-all restriction.  With this change, 312 executions\nreached the same ordering and every add_key() call failed with -EPERM.\n\nThe issue was found by manual concurrency analysis assisted by AI-based\nanalysis and independently verified with a QEMU reproducer and kernel\ninstrumentation.","publishedAt":"2026-10-23T12:21:59.288Z","updatedAt":"2026-10-30T12:41:13.694Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"24806fc9bca28fa1433bf938d1424dcb45d80e50","versionType":"git"},{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"9a5c2700336878465a630804a2d21864f22eca9c","versionType":"git"},{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"b3e404550dc2b7f3d4bb64b1da8005a1fa9a798d","versionType":"git"},{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"305f1828b871dd46bf41addeb6f11d2c162dcb25","versionType":"git"},{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"f99399b48e3edd6851fac34cd329bab9f1f33baf","versionType":"git"},{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"11516a0c402a6c1fa52254aa70d8d65fb921e59e","versionType":"git"},{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"da0b595d8e6e2dd798f6e34e09dc51a13b888514","versionType":"git"},{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"dd3ea3fcba7c75493760cdbccd35f029597e8d5e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["security/keys/key.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.7","versionType":"semver"},{"version":"5.10.273","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.224","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.113","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.11","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["security/keys/key.c"]}],"references":["https://git.kernel.org/stable/c/24806fc9bca28fa1433bf938d1424dcb45d80e50","https://git.kernel.org/stable/c/9a5c2700336878465a630804a2d21864f22eca9c","https://git.kernel.org/stable/c/b3e404550dc2b7f3d4bb64b1da8005a1fa9a798d","https://git.kernel.org/stable/c/305f1828b871dd46bf41addeb6f11d2c162dcb25","https://git.kernel.org/stable/c/f99399b48e3edd6851fac34cd329bab9f1f33baf","https://git.kernel.org/stable/c/11516a0c402a6c1fa52254aa70d8d65fb921e59e","https://git.kernel.org/stable/c/da0b595d8e6e2dd798f6e34e09dc51a13b888514","https://git.kernel.org/stable/c/dd3ea3fcba7c75493760cdbccd35f029597e8d5e"],"weaknesses":[],"ingestedAt":"2026-10-30T13:02:04.640Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/99xxx/CVE-2026-99040.json","commit":"cb14bf1b43b0c9f05f7f40eae2246263fd430780","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99040","state":"PUBLISHED","datePublished":"2026-10-23T12:21:59.288Z","dateUpdated":"2026-10-30T12:41:13.694Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.387Z"},"containers":{"cna":{"title":"KEYS: Fix add_key() race with keyring restriction","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nKEYS: Fix add_key() race with keyring restriction\n\n__key_create_or_update() snapshots keyring->restrict_link before taking\nthe destination keyring's semaphore.  keyring_restrict() installs a\nrestriction while holding that semaphore.\n\nThis allows a writer to observe no restriction, wait for the keyring\nowner to install a reject-all restriction and return successfully, and\nthen link a key using the stale NULL snapshot.  The writer only needs\nwrite permission on the destination keyring.\n\nMove the restrict_link read after __key_link_lock() and\n__key_link_begin().  The read and the subsequent restriction check are\nthen serialized with restriction installation by keyring->sem.\n\nThe race was reproduced on v7.2.8 in 19 executions where restriction\ninstallation returned before the link completed.  All 19 linked the key\ndespite the reject-all restriction.  With this change, 312 executions\nreached the same ordering and every add_key() call failed with -EPERM.\n\nThe issue was found by manual concurrency analysis assisted by AI-based\nanalysis and independently verified with a QEMU reproducer and kernel\ninstrumentation."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"24806fc9bca28fa1433bf938d1424dcb45d80e50","versionType":"git"},{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"9a5c2700336878465a630804a2d21864f22eca9c","versionType":"git"},{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"b3e404550dc2b7f3d4bb64b1da8005a1fa9a798d","versionType":"git"},{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"305f1828b871dd46bf41addeb6f11d2c162dcb25","versionType":"git"},{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"f99399b48e3edd6851fac34cd329bab9f1f33baf","versionType":"git"},{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"11516a0c402a6c1fa52254aa70d8d65fb921e59e","versionType":"git"},{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"da0b595d8e6e2dd798f6e34e09dc51a13b888514","versionType":"git"},{"version":"5ac7eace2d00eab5ae0e9fdee63e38aee6001f7c","status":"affected","lessThan":"dd3ea3fcba7c75493760cdbccd35f029597e8d5e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["security/keys/key.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.7","versionType":"semver"},{"version":"5.10.273","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.224","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.113","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.11","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["security/keys/key.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/24806fc9bca28fa1433bf938d1424dcb45d80e50"},{"url":"https://git.kernel.org/stable/c/9a5c2700336878465a630804a2d21864f22eca9c"},{"url":"https://git.kernel.org/stable/c/b3e404550dc2b7f3d4bb64b1da8005a1fa9a798d"},{"url":"https://git.kernel.org/stable/c/305f1828b871dd46bf41addeb6f11d2c162dcb25"},{"url":"https://git.kernel.org/stable/c/f99399b48e3edd6851fac34cd329bab9f1f33baf"},{"url":"https://git.kernel.org/stable/c/11516a0c402a6c1fa52254aa70d8d65fb921e59e"},{"url":"https://git.kernel.org/stable/c/da0b595d8e6e2dd798f6e34e09dc51a13b888514"},{"url":"https://git.kernel.org/stable/c/dd3ea3fcba7c75493760cdbccd35f029597e8d5e"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:41:13.694Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"5.10.273"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"5.15.224"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.12.113"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.18.57"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"7.2.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}