{"id":"CVE-2026-99040","published":"2026-10-23T13:17:27.360","lastModified":"2026-10-23T13:17:27.360","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.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/11516a0c402a6c1fa52254aa70d8d65fb921e59e","tags":[]},{"url":"https://git.kernel.org/stable/c/305f1828b871dd46bf41addeb6f11d2c162dcb25","tags":[]},{"url":"https://git.kernel.org/stable/c/da0b595d8e6e2dd798f6e34e09dc51a13b888514","tags":[]},{"url":"https://git.kernel.org/stable/c/dd3ea3fcba7c75493760cdbccd35f029597e8d5e","tags":[]},{"url":"https://git.kernel.org/stable/c/f99399b48e3edd6851fac34cd329bab9f1f33baf","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}