CVE-2026-72139

A flaw was found in the Linux kernel's TCP implementation. A race condition exists during the handling of TCP MD5 Signature (MD5Sig) keys when establishing a connection. A remote attacker could exploit this timing window, leading to a use-after-free vulnerability. This could result in a system crash (Denial of Service) or potentially arbitrary code execution.

This vulnerability is rated as Moderate severity rather than Important because successful exploitation requires specific prerequisites—namely, configuring TCP authentication options alongside MD5 keys on outbound sockets—and winning a narrow race condition during connection setup. In typical Red Hat deployments, these authentication mechanisms are restricted to specialized routing protocols rather than general networking services. In addition, supported Red Hat Enterprise Linux kernels do not incorporate the vulnerable upstream code paths.

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.