CVE-2026-67607: LightFTP 2.3.1 Race Condition DoS via worker_thread_cleanup
LightFTP 2.3.1 contains a residual race condition vulnerability (an incomplete fix for CVE-2024-11144) in the workerthreadcleanup() function of ftpserv.c that allows remote unauthenticated attackers to destabilize or crash the daemon by triggering unsynchronized access to shared per-connection state without holding the required mutex lock. Attackers can send a data-transfer command such as LIST followed immediately by ABOR to exploit the missing synchronization on shared context and detached thread id reuse, resulting in daemon destabilization or crash which can lead to a denial of service. The 2.3.1 patch only narrowed the timing window (an extra re-check and reordered cleanup), it never added the missing lock, so the underlying race remains.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
LightFTPto a version that resolves this vulnerability.Fixed in 2.3.1Patch CVE-2024-11144 - Compensating control
Mitigate the unauthenticated race/DoS by restricting network access to the LightFTP service (e.g., limit inbound connections to trusted IPs and/or isolate the host) until a fix is applied.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-67607?
The severity of CVE-2026-67607 is medium with a score of 5.9.
How does CVE-2026-67607 affect LightFTP?
CVE-2026-67607 affects LightFTP by allowing remote attackers to exploit a race condition to crash the server.
How do I fix CVE-2026-67607?
To fix CVE-2026-67607, update to the latest version of LightFTP that addresses the race condition vulnerability.
What type of vulnerability is CVE-2026-67607?
CVE-2026-67607 is classified as a race condition vulnerability.
What is the impact of an exploit of CVE-2026-67607?
Exploitation of CVE-2026-67607 can lead to a denial of service by crashing the LightFTP server.