# CVE-2026-67607: hfiref0x LightFTP race condition in worker thread cleanup

Source: https://junglewise.ai/threats/cve-2026-67607-hfiref0x-lightftp-race-condition-in-worker-thread-cleanup  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-31. Updated: 2026-07-31  
License: CC BY 4.0 with a link back

CVE-2026-67607 · Severity: medium · CVSS 5.9 · Published 2026-07-31

LightFTP is a lightweight file transfer server used to share files over a network. A flaw in how the server manages internal connections allows a remote attacker to cause the service to crash by timing specific requests. This results in a denial-of-service, preventing legitimate users from accessing or transferring files until the server is manually restarted.

Technologies: [Hfiref0x LightFTP](https://junglewise.ai/threats/technologies/lightftp). Vendors: [Hfiref0x](https://junglewise.ai/threats/vendors/hfiref0x).

## Quick answers

**Is CVE-2026-67607 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-67607 being exploited in the wild.

**How severe is CVE-2026-67607?** Medium severity, with a CVSS score of 5.9, published 31 July 2026.

**Which products and versions are affected?** Hfiref0x LightFTP <= 2.3.1.

**Is there a fix for CVE-2026-67607?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-67607 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-67607?** Check whether you run Hfiref0x LightFTP at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A Time-of-Check Time-of-Use (TOCTOU) race condition exists in LightFTP version 2.3.1 and earlier. The vulnerability occurs when a fresh connection reuses an FTP context while an ABRT cleanup is simultaneously in progress. Specifically, an unprotected re-check of WorkerThreadId occurs between the worker_thread_cleanup() and pthread_join() functions outside of the MTLock mutex. This allows an attacker to cause pthread_join() to operate on an invalid thread ID, triggering a server crash. This issue represents an incomplete fix for a previously identified vulnerability (CVE-2024-11144). Exploitation requires high timing precision but no authentication.

## Affected products

- hfiref0x LightFTP <= 2.3.1

## Timeline

- 2026-07-31: advisory: NVD and VulnCheck published the advisory

## References

- [https://github.com/zeroscience/tuktam](https://github.com/zeroscience/tuktam)
- [https://www.vulncheck.com/advisories/lightftp-race-condition-dos-via-worker-thread-cleanup](https://www.vulncheck.com/advisories/lightftp-race-condition-dos-via-worker-thread-cleanup)

## Related threats

- [LightFTP data race condition in ftpserv.c](https://junglewise.ai/threats/cve-2026-70637-lightftp-data-race-condition-in-ftpserv-c)
- [A buffer overflow in the g_cfg.MaxUsers component of LightFTP v2.0 allows attackers to cause a Denial of Service (DoS) via a crafted input.](https://junglewise.ai/threats/cve-2025-65403-a-buffer-overflow-in-the-g-cfg-maxusers-component-of-lightftp-v2)