In the Linux kernel, the following vulnerability has been resolved: rxrpc: only handle RESPONSE during service challenge Only process RESPONSE packets while the service connection is still in RXRPC_CONN_SERVICE_CHALLENGING. Check that state under state_lock before running response verification and security initialization, then use a local secured flag to decide whether to queue the secured-connection work after the state transition. This keeps duplicate or late RESPONSE packets from re-running the setup path and removes the unlocked post-transition state test.

A flaw was found in the `rxrpc` subsystem of the Linux kernel. This vulnerability allows for duplicate or late `RESPONSE` packets to be processed outside of the expected service challenging state. An attacker could potentially exploit this by sending specially crafted `RESPONSE` packets, leading to the re-execution of the setup path. This could result in unexpected system behavior or resource consumption.

RxRPC service challenges now ignore stray RESPONSE frames outside the expected state machine window. Red Hat classifies this as protocol hardening against duplicate/late packets. 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-2026-31676 https://nvd.nist.gov/vuln/detail/CVE-2026-31676 https://lore.kernel.org/linux-cve-announce/2026042543-CVE-2026-31676-ff79@gregkh/T