In the Linux kernel, the following vulnerability has been resolved: rxrpc: reject undecryptable rxkad response tickets rxkad_decrypt_ticket() decrypts the RXKAD response ticket and then parses the buffer as plaintext without checking whether crypto_skcipher_decrypt() succeeded. A malformed RESPONSE can therefore use a non-block-aligned ticket length, make the decrypt operation fail, and still drive the ticket parser with attacker-controlled bytes. Check the decrypt result and abort the connection with RXKADBADTICKET when ticket decryption fails.

A flaw was found in the Linux kernel's rxrpc subsystem. A remote attacker could exploit this by sending a malformed RXKAD response ticket. This ticket, with a non-block-aligned length, would cause decryption to fail, yet the system would proceed to process attacker-controlled data. This could lead to a denial of service, causing the connection to be aborted.

Malformed RXKAD tickets that cannot decrypt are now rejected instead of confusing later crypto paths. Red Hat classifies this as rxrpc hardening against untrusted peers. Red Hat Enterprise Linux 10 Fix deferred kernel Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Fix deferred kernel Red Hat Enterprise Linux 7 Fix deferred kernel-rt Red Hat Enterprise Linux 8 Fix deferred kernel Red Hat Enterprise Linux 8 Fix deferred kernel-rt Red Hat Enterprise Linux 9 Fix deferred kernel Red Hat Enterprise Linux 9 Fix deferred kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-31637 https://nvd.nist.gov/vuln/detail/CVE-2026-31637 https://lore.kernel.org/linux-cve-announce/2026042455-CVE-2026-31637-0433@gregkh/T