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CVE-2026-67607— LightFTP 2.3.1 Race Condition DoS via worker_thread_cleanup

Quick assessment

Affected
hfiref0x LightFTP
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

hfiref0x LightFTP是hfiref0x个人开发者开源的一个轻量级FTP服务。 hfiref0x LightFTP 2.3.1版本存在竞争条件问题漏洞，该漏洞源于竞争条件问题，远程攻击者可通过重用FTP上下文的连接与正在进行的ABRT清理竞争，利用worker_thread_cleanup()和pthread_join()之间在MTLock外未受保护的WorkerThreadId重新检查，导致pthread_join()对无效线程ID操作，造成服务器崩溃。

CVSS 5.9 · Medium EPSS 0.29% · P22

Affected Version Matrix 1

VendorProduct Version RangeStatus
hfiref0x LightFTP ≤ 2.3.1 affected
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I. Basic Information for CVE-2026-67607

Vulnerability Information
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Vulnerability Title
LightFTP 2.3.1 Race Condition DoS via worker_thread_cleanup
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
检查时间与使用时间(TOCTOU)的竞争条件
Source: CVE Program / CVE List V5
Vulnerability Title
hfiref0x LightFTP 竞争条件问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
hfiref0x LightFTP是hfiref0x个人开发者开源的一个轻量级FTP服务。 hfiref0x LightFTP 2.3.1版本存在竞争条件问题漏洞，该漏洞源于竞争条件问题，远程攻击者可通过重用FTP上下文的连接与正在进行的ABRT清理竞争，利用worker_thread_cleanup()和pthread_join()之间在MTLock外未受保护的WorkerThreadId重新检查，导致pthread_join()对无效线程ID操作，造成服务器崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
hfiref0x LightFTP 0 ~ 2.3.1 -

II. Public POCs for CVE-2026-67607

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III. Intelligence Information for CVE-2026-67607

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Vendor Advisories for CVE-2026-67607 (1)

Proof of Concept for CVE-2026-67607 (1)

IV. Related Vulnerabilities

Same product: LightFTP
Same vendor: hfiref0x
Same weakness: CWE-367

V. Comments for CVE-2026-67607

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