CVE-2026-23066

A flaw was found in the Linux kernel. A local unprivileged process can exploit an unsafe requeue path in the rxrpc_recvmsg function by using AF_RXRPC sockets with MSG_DONTWAIT and MSG_PEEK flags. This improper handling of the receive message queue can lead to memory corruption, such as Use-After-Frees (UAFs) or reference count underruns. The most likely outcome is a kernel crash or memory safety warning, resulting in a denial of service. There is also a conservative possibility of broader impact if the memory corruption is exploitable.

An unsafe requeue path in rxrpc_recvmsg can corrupt the recvmsg queue because a call is requeued unconditionally even if it is already on the queue due to MSG_PEEK or a concurrent IO thread requeue. This can corrupt the linked list bookkeeping and can manifest as use after free or refcount underrun in RXRPC call objects. The most likely outcome is a kernel crash or memory safety warning which results in denial of service. For the CVSS the PR is N because a local unprivileged process can trigger the behavior by using AF_RXRPC sockets and recvmsg with MSG_DONTWAIT and MSG_PEEK patterns. The issue is not directly network reachable as a pure remote packet trigger because the vulnerable operation is in the local recvmsg path. Remote traffic can influence timing and queue state but a local caller is still needed to exercise the buggy logic. Impact is primarily availability with a conservative possibility of broader impact if the memory corruption is exploitable.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, prevent module rxrpc from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.