CVE-2022-50676: 
Linux Kernel vulnerability analysis and mitigation

CVE-2022-50676 is a locking/concurrency vulnerability in the Linux kernel's RDS (Reliable Datagram Sockets) over TCP subsystem. The flaw was introduced by commit ac3615e7f3cffe2a ("RDS: TCP: Reduce code duplication in rds_tcp_reset_callbacks()"), which incorrectly placed cancel_delayed_work_sync() inside a lock_sock()-protected section in rds_tcp_reset_callbacks(), creating a potential deadlock condition. The vulnerability was publicly disclosed on December 9, 2025, and affects Linux kernel versions from the introduction of commit ac3615e7f3cffe2a up to the respective stable-branch fix commits. Feedly estimates the severity as Medium, and the EPSS score is approximately 0.033% (Feedly, EUVD).

The root cause is an improper locking order (CWE-667: Improper Locking) in the Linux kernel's net/rds/tcp.c. Commit ac3615e7f3cffe2a added cancel_delayed_work_sync() within a lock_sock()-protected critical section; however, rds_send_xmit() can also call lock_sock(), creating a lock dependency cycle that syzbot detected as a lockdep warning. The fix removes cancel_delayed_work_sync() from the lock_sock() section, which is safe because even if rds_{send,recv}_worker() re-queues work while __flush_work() is waiting, the retried worker becomes a no-op due to the absence of the RDS_CONN_UP bit. Patches were applied across multiple stable branches, with fix commits including e3cb25d3, 5d2ba255, 2425007c, 360aa721, da349221, 30bfa5aa, c380c28a, afe7053c, and a91b750f (Feedly, EUVD).

Successful triggering of this vulnerability can cause a kernel deadlock in systems using RDS over TCP, leading to a denial of service (system hang or kernel panic) on the affected host. The availability impact is the primary concern, as the deadlock can render the system unresponsive. Confidentiality and integrity are not directly affected by this locking bug (Feedly).

There is no known public exploit code or evidence of in-the-wild exploitation for CVE-2022-50676. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. The EPSS score is approximately 0.033%, reflecting a very low probability of exploitation in the near term. Detection coverage exists via Nessus plugins 278323 and 298924 (Feedly, Tenable).

Apply the appropriate stable kernel update containing the fix for your branch: 4.9.331, 4.14.296, 4.19.262, 5.4.220, 5.10.150, 5.15.75, 5.19.17, 6.0.3, or 6.1+. The fix is also included in Amazon Linux 2 kernel 5.15 via ALAS2KERNEL-5.15-2025-090. No configuration-based workaround is documented; upgrading to a patched kernel version is the recommended remediation (EUVD, Amazon Linux Advisory).