CVE-2026-74377

A flaw was found in the Linux kernel's Remote Direct Memory Access (RDMA) subsystem, specifically within the rxe driver. A local malicious user can exploit this by modifying Work Queue Entry (WQE) fields in a shared queue buffer that is mapped into userspace. This manipulation occurs while the kernel is processing the WQE for non-Shared Receive Queue (SRQ) Queue Pairs (QPs). The vulnerability leads to out-of-bounds reads, which can result in information disclosure or system instability.

A TOCTOU flaw in the RDMA rxe non SRQ receive path allows a local malicious user to modify a receive WQE in the userspace mapped queue while the kernel responder is processing it. Fields such as num_sge or SGE entries can change between validation and use, which can cause out of bounds reads in rxe_resp_check_length() and copy_data(). For the CVSS the PR:L is used because triggering requires local access to RDMA rxe user objects and the shared receive queue, but does not normally require full administrative privileges. AC:H is used because reliable triggering depends on a race window while the kernel processes the WQE. The issue is not directly network reachable by itself, although RDMA traffic may be used to drive responder processing after a local user has prepared the QP. Impact is at least local denial of service via kernel crash and in the paranoid case may allow limited confidentiality or integrity impact due to kernel OOB reads and unstable descriptor processing.

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.