# CVE-2026-70637: LightFTP 2.4 Data Race Condition via ABOR Command in ftpserv.c

Status: published. Published: 2026-08-06. Updated: 2026-11-08.

LightFTP through 2.4 contains multiple data race vulnerabilities in ftpserv.c that allow anonymous attackers to cause undefined behavior by issuing LIST followed by ABOR commands without authentication. The control thread closes data_socket and file_fd descriptors while worker threads concurrently operate on the same fields in worker_thread_cleanup, allowing stale file descriptors to be reassigned by the OS and subsequently used by worker threads on unrelated resources, resulting in potential denial of service.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- hfiref0x / LightFTP (hfiref0x/LightFTP): ≥ 0; ≤ 2.4 (affected, custom); ≥ 0; ≤ d28c5e08aa4bd128737d35cc6ee0f9630a910ed5 (affected, git). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 8.2 (high); 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; source: CNA: VulnCheck

- CVSS 3.1: 5.9 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: 0.36% as of 2026-11-08; percentile 30.52%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-820

## Exploit evidence

- exploit: https://github.com/hfiref0x/LightFTP/issues/75 (CNA: VulnCheck)

## References

- https://github.com/hfiref0x/LightFTP/issues/75 (CNA: VulnCheck; technical-description, exploit, issue-tracking)

- https://www.vulncheck.com/advisories/lightftp-data-race-condition-via-abor-command-in-ftpserv-c (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-70637; retrieved 2026-11-08; source updated 2026-11-08

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-70637; retrieved 2026-11-08; source updated Not reported

Revision: bcb1b82ac192bf0c563dbe5e2a1fe90e5b830dc58702fd98ee368fc66de23f7a

Canonical: https://y2.dev/cve/CVE-2026-70637

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