CVE-2026-99054 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Linux distribution maintainers, and users of Linux systems that use TIPC, as well as operators, security teams, and vulnerability management teams responsible for monitoring and securing Linux systems, should verify Linux kernel versions and update to fixed versions if necessary, review compensating controls, and monitor system logs for potential issues

Why it matters

A race condition vulnerability in the Linux kernel's TIPC subsystem can lead to teardown failures and potential use-after-free bugs, requiring verification of Linux kernel versions and monitoring of system logs.

• Verify Linux kernel versions and update to fixed versions if necessary
• Monitor system logs for potential use-after-free bugs and refcount_t addition on 0 errors
• Review and apply source code changes to ensure TIPC workqueues are properly destroyed

Technical summary

The Linux kernel's TIPC subsystem has a race condition vulnerability that can lead to teardown failures and potential use-after-free bugs. The vulnerability is caused by the improper destruction of workqueues before closing connections, allowing socket callbacks and subscription events to queue more work. This can result in a refcount_t addition on 0 from conn_get() on a connection whose release was blocked on idr_lock, a subsequent use-after-free in tipc_conn_close(), queue_work() on an already destroyed workqueue from the listener data-ready callback, and an RCU stall in tipc_topsrv_exit_net() while the walk spins under idr_lock. Affected product deployments should review and apply source code changes to fix

Defensive priority

High

Recommended defensive actions

• Review and apply the provided source code changes to ensure the TIPC workqueues are properly destroyed before closing connections
• Verify the Linux kernel version and update to a fixed version if necessary
• Monitor system logs for potential use-after-free bugs and refcount_t addition on 0 errors
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review compensating controls for exposed systems while remediation is scheduled and verified

Evidence notes

The CVE record and source item provide details about the vulnerability, including its description, affected versions, and references to source code changes. However, the corpus does not establish versions, exploitation, impact, or remediation beyond the provided official sources.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.