{"id":"CVE-2026-31637","state":"PUBLISHED","title":"rxrpc: reject undecryptable rxkad response tickets","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: reject undecryptable rxkad response tickets\n\nrxkad_decrypt_ticket() decrypts the RXKAD response ticket and then\nparses the buffer as plaintext without checking whether\ncrypto_skcipher_decrypt() succeeded.\n\nA malformed RESPONSE can therefore use a non-block-aligned ticket\nlength, make the decrypt operation fail, and still drive the ticket\nparser with attacker-controlled bytes.\n\nCheck the decrypt result and abort the connection with RXKADBADTICKET\nwhen ticket decryption fails.","publishedAt":"2026-04-24T14:44:51.364Z","updatedAt":"2026-10-19T18:56:01.051Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"252157d939d179b5d767cb860ff8fa7f8723b67a","versionType":"git"},{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"a75b3b361dd481d942c5f259a82d59718a41092c","versionType":"git"},{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"b3a808cd0790b5075aaa2bc3588edf02cd71d352","versionType":"git"},{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"47073aab8a3a5a7b41c9bd37d2a3dcbeeccd6c8a","versionType":"git"},{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"a149dcae23309df9de1c3b6b5d468610ef5ab7de","versionType":"git"},{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"22f6258e7b31dba9bf88dce4e3ee7f0f20072e60","versionType":"git"},{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"58fcd1b156152613ba00a064a129fb69507ddd7d","versionType":"git"},{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"fe4447cd95623b1cfacc15f280aab73a6d7340b2","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/rxrpc/rxkad.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.22","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.22","versionType":"semver"},{"version":"5.10.258","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.135","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.82","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.23","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.13","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/rxrpc/rxkad.c"]}],"references":["https://git.kernel.org/stable/c/252157d939d179b5d767cb860ff8fa7f8723b67a","https://git.kernel.org/stable/c/a75b3b361dd481d942c5f259a82d59718a41092c","https://git.kernel.org/stable/c/b3a808cd0790b5075aaa2bc3588edf02cd71d352","https://git.kernel.org/stable/c/47073aab8a3a5a7b41c9bd37d2a3dcbeeccd6c8a","https://git.kernel.org/stable/c/a149dcae23309df9de1c3b6b5d468610ef5ab7de","https://git.kernel.org/stable/c/22f6258e7b31dba9bf88dce4e3ee7f0f20072e60","https://git.kernel.org/stable/c/58fcd1b156152613ba00a064a129fb69507ddd7d","https://git.kernel.org/stable/c/fe4447cd95623b1cfacc15f280aab73a6d7340b2","https://cert-portal.siemens.com/productcert/html/ssa-784472.html"],"weaknesses":["CWE-754"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/31xxx/CVE-2026-31637.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31637","state":"PUBLISHED","datePublished":"2026-04-24T14:44:51.364Z","dateUpdated":"2026-10-19T18:56:01.051Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-03-09T15:48:24.125Z"},"containers":{"cna":{"title":"rxrpc: reject undecryptable rxkad response tickets","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: reject undecryptable rxkad response tickets\n\nrxkad_decrypt_ticket() decrypts the RXKAD response ticket and then\nparses the buffer as plaintext without checking whether\ncrypto_skcipher_decrypt() succeeded.\n\nA malformed RESPONSE can therefore use a non-block-aligned ticket\nlength, make the decrypt operation fail, and still drive the ticket\nparser with attacker-controlled bytes.\n\nCheck the decrypt result and abort the connection with RXKADBADTICKET\nwhen ticket decryption fails."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"252157d939d179b5d767cb860ff8fa7f8723b67a","versionType":"git"},{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"a75b3b361dd481d942c5f259a82d59718a41092c","versionType":"git"},{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"b3a808cd0790b5075aaa2bc3588edf02cd71d352","versionType":"git"},{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"47073aab8a3a5a7b41c9bd37d2a3dcbeeccd6c8a","versionType":"git"},{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"a149dcae23309df9de1c3b6b5d468610ef5ab7de","versionType":"git"},{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"22f6258e7b31dba9bf88dce4e3ee7f0f20072e60","versionType":"git"},{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"58fcd1b156152613ba00a064a129fb69507ddd7d","versionType":"git"},{"version":"17926a79320afa9b95df6b977b40cca6d8713cea","status":"affected","lessThan":"fe4447cd95623b1cfacc15f280aab73a6d7340b2","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/rxrpc/rxkad.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.22","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.22","versionType":"semver"},{"version":"5.10.258","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.135","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.82","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.23","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.13","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/rxrpc/rxkad.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/252157d939d179b5d767cb860ff8fa7f8723b67a"},{"url":"https://git.kernel.org/stable/c/a75b3b361dd481d942c5f259a82d59718a41092c"},{"url":"https://git.kernel.org/stable/c/b3a808cd0790b5075aaa2bc3588edf02cd71d352"},{"url":"https://git.kernel.org/stable/c/47073aab8a3a5a7b41c9bd37d2a3dcbeeccd6c8a"},{"url":"https://git.kernel.org/stable/c/a149dcae23309df9de1c3b6b5d468610ef5ab7de"},{"url":"https://git.kernel.org/stable/c/22f6258e7b31dba9bf88dce4e3ee7f0f20072e60"},{"url":"https://git.kernel.org/stable/c/58fcd1b156152613ba00a064a129fb69507ddd7d"},{"url":"https://git.kernel.org/stable/c/fe4447cd95623b1cfacc15f280aab73a6d7340b2"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable path is reached by remote RxRPC RESPONSE packets over UDP to a listening AF_RXRPC service connection.\nAC:L - An attacker can initiate the connection, receive the server challenge, and craft a non-block-aligned ticket plus matching response using an attacker-chosen session key; no race or uncontrolled condition is required.\nPR:N - The flaw is in the authentication handshake before client credentials are validated, so a network attacker needs no prior privileges or valid rxkad ticket.\nUI:N - Exploitation only requires sending protocol packets to the service; no victim user action is needed.\nS:U - The impact remains within the kernel/RxRPC service security authority and does not cross a VM, IOMMU, or similar security boundary.\nC:H - The bug can bypass rxkad authentication and let an unauthenticated peer access data exposed by a protected RxRPC service in the highest reasonable deployment.\nI:H - A forged authenticated connection can issue arbitrary service RPCs and choose/downgrade the connection security level, enabling unauthorized modification of protected service state.\nA:H - In a severe RxRPC service deployment, the same authentication bypass can be used to invoke destructive or service-disrupting authenticated operations repeatedly over the 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