CVE-2026-74433

A flaw was found in the Linux kernel's rxrpc component, specifically within the rxgk_issue_challenge() function. This Use-After-Free (UAF) vulnerability occurs because a memory page containing challenge content is prematurely freed before a tracepoint invocation, causing a pointer to reference freed memory. This could allow a local attacker to potentially cause a denial of service or achieve arbitrary code execution.

A use-after-free can occur in rxgk_issue_challenge() because the page holding the challenge packet is freed before trace_rxrpc_tx_packet() uses whdr that points into that page. The visible primitive is a stale pointer read in the tracepoint path rather than an obvious write primitive, so the realistic impact is limited denial of service or diagnostic UAF when tracing or debug checks are active. For the CVSS the PR:N is used for the paranoid network case because a remote peer may trigger challenge generation without local user access when the RxRPC rxgk service and tracing path are reachable. The issue is network reachable in affected RxRPC deployments, but practical triggering depends on non-default rxgk usage and tracepoint or debug visibility. Impact is at least availability loss and in the paranoid case may include limited confidentiality or integrity impact due to the use-after-free class, so it should be reviewed manually.

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.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.