{"id":"CVE-2026-31719","state":"PUBLISHED","title":"crypto: krb5enc - fix async decrypt skipping hash verification","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: krb5enc - fix async decrypt skipping hash verification\n\nkrb5enc_dispatch_decrypt() sets req->base.complete as the skcipher\ncallback, which is the caller's own completion handler. When the\nskcipher completes asynchronously, this signals \"done\" to the caller\nwithout executing krb5enc_dispatch_decrypt_hash(), completely bypassing\nthe integrity verification (hash check).\n\nCompare with the encrypt path which correctly uses\nkrb5enc_encrypt_done as an intermediate callback to chain into the\nhash computation on async completion.\n\nFix by adding krb5enc_decrypt_done as an intermediate callback that\nchains into krb5enc_dispatch_decrypt_hash() upon async skcipher\ncompletion, matching the encrypt path's callback pattern.\n\nAlso fix EBUSY/EINPROGRESS handling throughout: remove\nkrb5enc_request_complete() which incorrectly swallowed EINPROGRESS\nnotifications that must be passed up to callers waiting on backlogged\nrequests, and add missing EBUSY checks in krb5enc_encrypt_ahash_done\nfor the dispatch_encrypt return value.\n\n\nUnset MAY_BACKLOG on the async completion path so the user won't\nsee back-to-back EINPROGRESS notifications.","publishedAt":"2026-05-01T13:56:13.385Z","updatedAt":"2026-10-19T19:06:07.136Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d1775a177f7f38156d541c8a3e3c91eaa6e69699","status":"affected","lessThan":"07cbb1bd424370671814a862913c99a6e1441588","versionType":"git"},{"version":"d1775a177f7f38156d541c8a3e3c91eaa6e69699","status":"affected","lessThan":"e51f42114abbdf47f29dda43e7826be28907fcd2","versionType":"git"},{"version":"d1775a177f7f38156d541c8a3e3c91eaa6e69699","status":"affected","lessThan":"3bfbf5f0a99c991769ec562721285df7ab69240b","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["crypto/krb5enc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.15","versionType":"semver"},{"version":"6.18.25","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.2","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["crypto/krb5enc.c"]}],"references":["https://git.kernel.org/stable/c/07cbb1bd424370671814a862913c99a6e1441588","https://git.kernel.org/stable/c/e51f42114abbdf47f29dda43e7826be28907fcd2","https://git.kernel.org/stable/c/3bfbf5f0a99c991769ec562721285df7ab69240b"],"weaknesses":["CWE-354"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/31xxx/CVE-2026-31719.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31719","state":"PUBLISHED","datePublished":"2026-05-01T13:56:13.385Z","dateUpdated":"2026-10-19T19:06:07.136Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-03-09T15:48:24.134Z"},"containers":{"cna":{"title":"crypto: krb5enc - fix async decrypt skipping hash verification","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: krb5enc - fix async decrypt skipping hash verification\n\nkrb5enc_dispatch_decrypt() sets req->base.complete as the skcipher\ncallback, which is the caller's own completion handler. When the\nskcipher completes asynchronously, this signals \"done\" to the caller\nwithout executing krb5enc_dispatch_decrypt_hash(), completely bypassing\nthe integrity verification (hash check).\n\nCompare with the encrypt path which correctly uses\nkrb5enc_encrypt_done as an intermediate callback to chain into the\nhash computation on async completion.\n\nFix by adding krb5enc_decrypt_done as an intermediate callback that\nchains into krb5enc_dispatch_decrypt_hash() upon async skcipher\ncompletion, matching the encrypt path's callback pattern.\n\nAlso fix EBUSY/EINPROGRESS handling throughout: remove\nkrb5enc_request_complete() which incorrectly swallowed EINPROGRESS\nnotifications that must be passed up to callers waiting on backlogged\nrequests, and add missing EBUSY checks in krb5enc_encrypt_ahash_done\nfor the dispatch_encrypt return value.\n\n\nUnset MAY_BACKLOG on the async completion path so the user won't\nsee back-to-back EINPROGRESS notifications."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d1775a177f7f38156d541c8a3e3c91eaa6e69699","status":"affected","lessThan":"07cbb1bd424370671814a862913c99a6e1441588","versionType":"git"},{"version":"d1775a177f7f38156d541c8a3e3c91eaa6e69699","status":"affected","lessThan":"e51f42114abbdf47f29dda43e7826be28907fcd2","versionType":"git"},{"version":"d1775a177f7f38156d541c8a3e3c91eaa6e69699","status":"affected","lessThan":"3bfbf5f0a99c991769ec562721285df7ab69240b","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["crypto/krb5enc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.15","versionType":"semver"},{"version":"6.18.25","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.2","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["crypto/krb5enc.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/07cbb1bd424370671814a862913c99a6e1441588"},{"url":"https://git.kernel.org/stable/c/e51f42114abbdf47f29dda43e7826be28907fcd2"},{"url":"https://git.kernel.org/stable/c/3bfbf5f0a99c991769ec562721285df7ab69240b"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable AEAD decrypt path is used by Kerberos crypto for network-facing consumers such as RxRPC/AFS and Ceph. A remote peer or network attacker can supply or tamper with encrypted protocol packets that reach `crypto_krb5_decrypt()` and then `krb5enc_decrypt()`.\nAC:L - There is no attacker-uncontrolled race; on a vulnerable deployment using an asynchronous skcipher provider, the bypass follows directly from an async decrypt completion. When uncertain about async-provider deployment details, the higher-severity Low complexity is selected.\nPR:N - The attack can be carried in network traffic toward a kernel network filesystem/protocol endpoint and does not require local privileges on the target. In the strongest plausible scenario, a network attacker tampering with an existing protected flow needs no target-system account.\nUI:N - No victim user action is required once the affected service or client connection is active. Packet processing reaches the vulnerable decrypt path automatically.\nS:U - The impact remains within the kernel/protocol security authority handling the protected traffic. This is not a VM escape, sandbox escape, or cross-authority boundary violation.\nC:N - The bug skips integrity verification after decryption but does not by itself disclose plaintext or kernel memory. I found no memory corruption or read primitive associated with the fix.\nI:H - An async decrypt can complete successfully without checking the Kerberos checksum, allowing tampered ciphertext to be accepted as authenticated plaintext. For network storage/filesystem protocols, that can permit forgery or unauthorized modification of protected protocol data.\nA:N - The fixed flaw is an authentication/integrity bypass, and the investigation did not identify a new kernel crash, hang, or resource exhaustion primitive. Bad packets may be rejected or abort protocol state, but that is not a distinct high-availability impact from this bug."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:24:50.735Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"6.18.25"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"7.0.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-31719","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T15:12:50.260721Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-354","lang":"en","type":"CWE","description":"CWE-354 Improper Validation of Integrity Check Value"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T19:06:07.136Z"}}]}}}