# CVE-2019-25686: Core FTP 2.0 build 653 PBSZ Unauthenticated Denial of Service

> Unauthenticated attackers can crash the Core FTP service by sending a malformed PBSZ command with an oversized buffer.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/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:** 5 Apr 2026
- **Updated:** 6 Apr 2026
- **Also known as:** GHSA-frgr-r4xw-r3ph

## What is CVE-2019-25686?

CVE-2019-25686 is a high-severity denial of service vulnerability in Coreftp Core FTP, published on 5 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Core FTP 2.0 build 653 contains a denial of service vulnerability in the PBSZ command that allows unauthenticated attackers to crash the service by sending a malformed command with an oversized buffer. Attackers can send a PBSZ command with a payload exceeding 211 bytes to trigger an access violation and crash the FTP server process.

Weakness: CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2019-25686?

It affects 1 product.


Products: Coreftp Core Ftp.

## How do I fix CVE-2019-25686?

No fix has been published for CVE-2019-25686 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-25686 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2019-25686 exists.

## Other vulnerabilities in Coreftp Core FTP

- [CVE-2020-19596](https://insights.sbomify.com/CVE-2020-19596/): Memory corruption in n/a (critical 9.8)
- [CVE-2018-12113](https://insights.sbomify.com/CVE-2018-12113/): Memory corruption in n/a (critical 9.8)
- [CVE-2013-3930](https://insights.sbomify.com/CVE-2013-3930/): Memory corruption in n/a (critical 9.3)
- [CVE-2009-3484](https://insights.sbomify.com/CVE-2009-3484/): Memory corruption in n/a (critical 9.3)
- [CVE-2019-25654](https://insights.sbomify.com/CVE-2019-25654/): Core FTP/SFTP Server 1.2 Denial of Service via Buffer Overflow (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-25686 and fix it if it is affected.

What it is: CVE-2019-25686 is a high-severity denial of service vulnerability in Coreftp Core FTP, published on 5 Apr 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-2019-25686 exists.

Affected product: Coreftp Core FTP. 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-2019-25686/ (Markdown: https://insights.sbomify.com/CVE-2019-25686/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-25686
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-25686
- OSV: https://osv.dev/vulnerability/CVE-2019-25686

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-25686/
Summaries are generated and may contain mistakes; the official description above is the record.