CVE-2026-74719

A flaw was found in the Linux kernel's Server Message Block (SMB) over Remote Direct Memory Access (RDMA) (SMC) protocol implementation. A remote attacker, by sending a duplicate link confirmation or addition request, can cause a memory leak. This occurs because the system overwrites an existing memory allocation without freeing the previous one, potentially leading to a denial of service over time due to resource exhaustion.

A moderate severity flaw was found in the Linux kernel's Shared Memory Communications over RDMA (SMC) link layer control (LLC) handling. In the SMC_LLC_CONFIRM_LINK / SMC_LLC_ADD_LINK_CONT branch of smc_llc_event_handler(), an incoming queue entry is stored into the active LLC flow without first checking whether an entry is already pending. A malicious or buggy SMC peer can exploit this by sending a duplicate CONFIRM_LINK or ADD_LINK_CONT request while a flow is active, causing the previously allocated entry to be overwritten without being freed and leaking one kernel allocation per spurious message. Repeated exploitation can gradually exhaust kernel memory and result in a denial of service of the affected system. The kernel and kernel-rt packages in Red Hat Enterprise Linux 8, 9, and 10 and in Red Hat In-Vehicle OS 2 are affected; Red Hat Enterprise Linux 6 and 7 are not affected because the vulnerable code is not present in those versions. This flaw is rated Moderate by Red Hat Product Security. Because exploitation requires a reachable SMC peer and results only in gradual memory exhaustion rather than memory corruption, privilege escalation, or information disclosure, the fix has been deferred for the affected Red Hat Enterprise Linux and Red Hat In-Vehicle OS versions and will be delivered in a future update; the residual risk is denial of service through sustained kernel memory exhaustion caused by an adjacent malicious or buggy SMC peer.

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 do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.