CVE-2025-64484 OAuth2-Proxy vulnerable to header smuggling via underscore, leading to potential privilege escalation
Authenticated users can bypass header filtering in OAuth2-Proxy by using underscores, potentially escalating privileges in upstream applications.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-64484?
CVE-2025-64484 is a high-severity vulnerability in oauth2-proxy, published on 10 Nov 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
OAuth2-Proxy is an open-source tool that can act as either a standalone reverse proxy or a middleware component integrated into existing reverse proxy or load balancer setups. In versions prior to 7.13.0, all deployments of OAuth2 Proxy in front of applications that normalize underscores to dashes in HTTP headers (e.g., WSGI-based frameworks such as Django, Flask, FastAPI, and PHP applications). Authenticated users can inject underscore variants of X-Forwarded-* headers that bypass the proxy’s filtering logic, potentially escalating privileges in the upstream app. OAuth2 Proxy authentication/authorization itself is not compromised. The problem has been patched with v7.13.0. By default all specified headers will now be normalized, meaning that both capitalization and the use of underscores (_) versus dashes (-) will be ignored when matching headers to be stripped. For example, both `X-Forwarded-For` and `X_Forwarded-for` will now be treated as equivalent and stripped away. For those who have a rational that requires keeping a similar looking header and not stripping it, the maintainers introduced a new configuration field for Headers managed through the AlphaConfig called `InsecureSkipHeaderNormalization`. As a workaround, ensure filtering and processing logic in upstream services don't treat underscores and hyphens in Headers the same way.
Weakness: CWE-644
Which versions are affected by CVE-2025-64484?
5 open source packages ship an affected version, including github.com/oauth2-proxy/oauth2-proxy/v7, oauth2-proxy and github.com/oauth2-proxy/oauth2-proxy.
| Package | Affected | Fixed in |
|---|---|---|
github.com/oauth2-proxy/oauth2-proxy/v7 Go | All versions | 7.13.0 |
github.com/oauth2-proxy/oauth2-proxy/v7 Go | All versions | 7.13.0 |
github.com/oauth2-proxy/oauth2-proxy/v7 Go | All versions | 7.13.0 |
oauth2-proxy Bitnami | All versions | 7.13.0 |
github.com/oauth2-proxy/oauth2-proxy Go | All versions | None |
How do I fix CVE-2025-64484?
Upgrade github.com/oauth2-proxy/oauth2-proxy/v7 to 7.13.0 or later.
Is CVE-2025-64484 being exploited?
There is no known exploitation of CVE-2025-64484 in the wild and no public exploit code.
Sources
Also known as BIT-oauth2-proxy-2025-64484, GHSA-vjrc-mh2v-45x6, GO-2025-4113, MINI-5375-w6xw-hhcf, MINI-qqjw-h9g5-7vvx.