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

> Anonymous attackers can cause denial of service in LightFTP by exploiting a data race condition between LIST and ABOR commands.

- **Severity:** High 8.2 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 6 Aug 2026
- **Updated:** 14 Aug 2026
- **Also known as:** GHSA-6269-2q48-xxqm

## What is CVE-2026-70637?

CVE-2026-70637 is a high-severity vulnerability in hfiref0x LightFTP, published on 6 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-820 (Missing Synchronization)

## Which versions are affected by CVE-2026-70637?


## How do I fix CVE-2026-70637?

No fix has been published for CVE-2026-70637 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-70637 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-70637 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-70637 and fix it if it is affected.

What it is: CVE-2026-70637 is a high-severity vulnerability in hfiref0x LightFTP, published on 6 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-70637 exists.

Affected product: hfiref0x LightFTP. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-70637/ (Markdown: https://insights.sbomify.com/CVE-2026-70637/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-70637
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-70637
- OSV: https://osv.dev/vulnerability/CVE-2026-70637

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-70637/
Summaries are generated and may contain mistakes; the official description above is the record.