---
id: CVE-2026-40575
title: >-
  oauth2-proxy: github.com/oauth2-proxy/oauth2-proxy: OAuth2 Proxy:
  Authentication bypass due to spoofed X-Forwarded-Uri header (CVE-2026-405…
summary: >-
  A flaw was found in OAuth2 Proxy. When configured with `--reverse-proxy` and
  either `--skip-auth-regex` or `--skip-auth-route`, the proxy may trust a
  client-supplied `X-Forwarded-Uri` header. An unauthenticated remote attacker
  can exploit …
severity: high
cvss: 8.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N'
cvssSource: vendor
cwe: CWE-290
vendor: Red Hat
product: Red Hat Hardened Images
affected:
  - ceph_storage 9
  - hardened_images
patched:
  - hardened_images
published: '2026-04-21'
updated: '2026-09-21'
sourceUpdated: '2026-09-21T16:40:43+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40575.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40575.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-40575'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2460449'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-40575'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-40575'
  - url: >-
      https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-7x63-xv5r-3p2x
  - url: 'https://access.redhat.com/errata/RHSA-2026:58471'
  - url: 'https://github.com/oauth2-proxy/oauth2-proxy'
tags:
  - csaf
  - vex
  - red-hat
  - osv
  - go
epss: 0.00732
epssPercentile: 0.52312
aliases:
  - GHSA-7x63-xv5r-3p2x
  - BIT-oauth2-proxy-2026-40575
  - GO-2026-5236
ecosystem: go
scores:
  vendor: 8.7
  osv: 9.1
ingestedAt: '2026-07-21T19:04:58.367Z'
---

## Overview

A flaw was found in OAuth2 Proxy. When configured with `--reverse-proxy` and either `--skip-auth-regex` or `--skip-auth-route`, the proxy may trust a client-supplied `X-Forwarded-Uri` header. An unauthenticated remote attacker can exploit this by spoofing the header, leading to an authentication bypass. This allows unauthorized access to protected routes without a valid session.

## Vendor advisories

- **RHSA-2026:58471** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:58471)
- **Red Hat VEX** · Important · affected: Red Hat Ceph Storage 9 · no fix planned: Red Hat Ceph Storage 9 · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40575.json)

**oauth2-proxy: github.com/oauth2-proxy/oauth2-proxy: OAuth2 Proxy: Authentication bypass due to spoofed X-Forwarded-Uri header** — rated Important by Red Hat. Released 2026-04-21, updated 2026-09-21.

Affected:

- Red Hat Ceph Storage 9

Fixed:

- Red Hat Hardened Images

No fix planned:

- Red Hat Ceph Storage 9

## Remediation

For details on how to apply this update, which includes the changes described in this advisory, refer to:
https://images.redhat.com/ https://access.redhat.com/errata/RHSA-2026:58471

Workarounds / mitigations:

- This issue can be mitigated by one of the options bellow:

1) Strip any client-provided `X-Forwarded-Uri` header at any layer before it reaches `oauth2-proxy`;
2) Overwrite the `X-Forwarded-Uri` header with the actual request URI before the request reaches `oauth2-proxy`. If you are using NGINX you can use the following example to create your tailored mitigation:

~~~
  location /internal-auth/ {
    internal; # Ensure external users can't access this path

    # Make sure the OAuth2 Proxy know…

## Package advisory (CVE-2026-40575)

Affected packages:

- `github.com/oauth2-proxy/oauth2-proxy/v7 >= 7.5.0, < 7.15.2`

Patched in:

- `github.com/oauth2-proxy/oauth2-proxy/v7 7.15.2`

Source: https://osv.dev/vulnerability/GHSA-7x63-xv5r-3p2x