CVE-2025-64484
published 2025-11-10CVE-2025-64484: 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…
PriorityP356high8.5CVSS 3.1
AVNACLPRLUINSCCHILAN
EPSS
0.63%
45.4th percentile
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.
Affected
2 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| github.com | oauth2-proxy_oauth2-proxy_v7 | >= 0 < 7.13.0 | 7.13.0 |
| oauth2-proxy | oauth2-proxy | < 7.13.0 | 7.13.0 |
CVSS provenance
nvdv3.18.5HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
vendor_redhat8.5HIGH
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OSV
OAuth2-Proxy is vulnerable to header smuggling via underscore leading to potential privilege escalation in github.com/oauth2-proxy/oauth2-proxy
osv·2025-11-17
CVE-2025-64484 OAuth2-Proxy is vulnerable to header smuggling via underscore leading to potential privilege escalation in github.com/oauth2-proxy/oauth2-proxy
OAuth2-Proxy is vulnerable to header smuggling via underscore leading to potential privilege escalation in github.com/oauth2-proxy/oauth2-proxy
OAuth2-Proxy is vulnerable to header smuggling via underscore leading to potential privilege escalation in github.com/oauth2-proxy/oauth2-proxy
OSV
OAuth2-Proxy is vulnerable to header smuggling via underscore leading to potential privilege escalation
osv·2025-11-12
CVE-2025-64484 [HIGH] OAuth2-Proxy is vulnerable to header smuggling via underscore leading to potential privilege escalation
OAuth2-Proxy is vulnerable to header smuggling via underscore leading to potential privilege escalation
### Impact
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.
### Patches
This change mitigates a request header smuggling vulnerability where an attacker could bypass header stripping by using different capitalization or replacing dashes with underscores. The problem has been patched with v7.13.0.
By defa
GHSA
OAuth2-Proxy is vulnerable to header smuggling via underscore leading to potential privilege escalation
ghsa·2025-11-12
CVE-2025-64484 [HIGH] CWE-644 OAuth2-Proxy is vulnerable to header smuggling via underscore leading to potential privilege escalation
OAuth2-Proxy is vulnerable to header smuggling via underscore leading to potential privilege escalation
### Impact
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.
### Patches
This change mitigates a request header smuggling vulnerability where an attacker could bypass header stripping by using different capitalization or replacing dashes with underscores. The problem has been patched with v7.13.0.
By defa
Red Hat
oauth2-proxy: OAuth2-Proxy vulnerable to header smuggling via underscore, leading to potential privilege escalation
vendor_redhat·2025-11-10·CVSS 8.5
CVE-2025-64484 [HIGH] CWE-644 oauth2-proxy: OAuth2-Proxy vulnerable to header smuggling via underscore, leading to potential privilege escalation
oauth2-proxy: OAuth2-Proxy vulnerable to header smuggling via underscore, leading to potential privilege escalation
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.
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
https://datatracker.ietf.org/doc/html/rfc2616#section-4.2https://datatracker.ietf.org/doc/html/rfc822#section-3.2https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-vjrc-mh2v-45x6https://github.security.telekom.com/2020/05/smuggling-http-headers-through-reverse-proxies.htmlhttps://www.uptimia.com/questions/why-are-http-headers-with-underscores-dropped-by-nginx
2025-11-10
Published