CVE-2025-64484

Published Nov 10, 2025

Last updated 17 days ago

Overview

AI description

Automated description summarized from trusted sources.

CVE-2025-64484 is a header-smuggling vulnerability found in OAuth2-Proxy's handling of HTTP headers containing underscores. The proxy fails to properly normalize these header names, potentially allowing crafted requests to bypass header validation or filtering. This vulnerability affects deployments of OAuth2-Proxy in front of applications that treat underscores and hyphens differently in HTTP headers, such as WSGI frameworks like Django, Flask, FastAPI, or PHP apps. An authenticated attacker could exploit this to inject or manipulate upstream headers, potentially gaining unauthorized access to protected endpoints or sensitive information. OAuth2 Proxy authentication/authorization itself is not compromised. The issue has been patched in version 7.13.0.

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.
Source: security-advisories@github.com
NVD status: Deferred

Risk scores

CVSS 3.1

Type: Secondary
Base score: 8.5
Impact score: 4.7
Exploitability score: 3.1
Vector string: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
Severity: HIGH

Weaknesses

security-advisories@github.com: CWE-644

Hype score: Not currently trending

References