Vulnerability in Hfiref0x Lightftp
CVE-2026-70637
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.004 (30.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 30th percentile — 30.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Hfiref0x Lightftp — versions 0
Weakness classification (CWE)
References
- github.com/hfiref0x/LightFTP/issues/75 (technical-description, exploit)
- www.vulncheck.com/advisories/lightftp-data-race-condition-via-abor-command-in-f… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-70637?
- CVE-2026-70637 is a medium-severity vulnerability in Hfiref0x Lightftp, classified under CWE-820. CVSS score: 5.9/10. Published 2026-08-06.
- How severe is CVE-2026-70637?
- Medium severity. CVSS v3 base score is 5.9 out of 10.