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Vulnerability record · CVE-2026-67607 · published 31 July 2026

CVE-2026-67607: TOCTOU race condition vulnerability

LightFTP 2.3.1 contains a residual race condition vulnerability (an incomplete fix for CVE-2024-11144) in the worker_thread_cleanup() 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.

8.2 CVSS 4.0 High EPSS 0.40% · top 68.9% CWE-367 · TOCTOU race condition Deferred
8.2CVSS 4.0 base score
0.40%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
3References
9 Sep 2026Last modified by NVD

Description

LightFTP 2.3.1 contains a residual race condition vulnerability (an incomplete fix for CVE-2024-11144) in the worker_thread_cleanup() 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.

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/zeroscience/tuktam#real-world-case-study-lightftp-cve-2024-11144
https://www.vulncheck.com/advisories/lightftp-race-condition-dos-via-worker-thread-cleanup
https://github.com/zeroscience/tuktam#real-world-case-study-lightftp-cve-2024-11144

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-67607), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.