CVE-2026-74719
Received Received - Intake

Memory Leak in Linux Kernel SMC Protocol

Publication date: 2026-08-22

Last updated on: 2026-08-22

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: net/smc: fix qentry overwrite for CONFIRM_LINK and ADD_LINK_CONT in smc_llc_event_handler() The SMC_LLC_CONFIRM_LINK / SMC_LLC_ADD_LINK_CONT branch in smc_llc_event_handler() stores an incoming qentry into the local LLC flow without first checking whether a qentry is already pending. If a malicious or buggy peer sends a second CONFIRM_LINK or ADD_LINK_CONT request while a flow is active and flow->qentry is already set, smc_llc_flow_qentry_set() overwrites the pointer without freeing the previous allocation, leaking one kmalloc-96 object per spurious message. The sibling SMC_LLC_DELETE_LINK branch already has the correct !flow->qentry guard. Apply the same guard to the CONFIRM_LINK/ADD_LINK_CONT branch so that a duplicate message when qentry is already occupied falls through to break and is freed by the kfree(qentry) at the out: label, rather than silently leaking the existing allocation. The response direction (smc_llc_rx_response()) is unaffected: it already guards with flow->qentry at the equivalent site and drops duplicate responses correctly.

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Meta Information

Published
2026-08-22
Last Modified
2026-08-22
Generated
2026-08-22
AI Q&A
2026-08-22
EPSS Evaluated
N/A
NVD
CVE-2026-74719
EUVD
EUVD-2026-64406

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a memory leak in the SMC (Socket Direct) protocol implementation. When a peer sends duplicate CONFIRM_LINK or ADD_LINK_CONT messages while a flow is active, the kernel overwrites the existing qentry pointer without freeing the previous memory allocation. This causes a kmalloc-96 object to leak per duplicate message.

Detection Guidance

This vulnerability is specific to the Linux kernel's SMC (Socket Direct) protocol implementation and requires kernel-level inspection. Detection involves checking kernel logs for SMC-related errors or monitoring for kmalloc-96 memory leaks. Use commands like dmesg | grep smc or journalctl -k | grep smc to inspect SMC-related events. If duplicate CONFIRM_LINK or ADD_LINK_CONT messages are processed, it may indicate exploitation.

Impact Analysis

This vulnerability could lead to memory exhaustion on affected systems over time due to the gradual accumulation of leaked memory objects. This may cause performance degradation or system instability if the leaked memory is not properly managed.

Mitigation Strategies

Apply the latest kernel security patches from your Linux distribution to ensure the fix for CVE-2026-74719 is included. If patching is not immediately possible, consider disabling the SMC protocol module (smc) by blacklisting it or restricting its use via kernel parameters. Monitor network traffic for suspicious SMC protocol activity.

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