---
title: "CVE-2026-20896: Gitea Docker image: `REVERSE_PROXY_TRUSTED_PROXIES = *` default lets any source IP impersonate any user via `X-WEBAUTH-USER`"
url: https://erroneo.us/security/cve/CVE-2026-20896/
description: "CVE-2026-20896 (code.gitea.io/gitea (Go)): Gitea Docker image versions up to and including 1.26.2 use REVERSEPROXYTRUSTEDPROXIES= by default, allowing any…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-07-03
date_modified: 2026-07-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-20896"
kev: false
cvss: 9.8
epss: 0.02755
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-20896: Gitea Docker image: `REVERSE_PROXY_TRUSTED_PROXIES = *` default lets any source IP impersonate any user via `X-WEBAUTH-USER`

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 2.8% , percentile 86: FIRST’s model estimates a 2.8% chance of exploitation activity in the next 30 days, higher than 86% of all scored CVEs (elevated). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes code.gitea.io/gitea (Go) < 1.26.3, fixed in 1.26.3 . Check your lockfile, including transitive dependencies.

## What it is

Gitea Docker image versions up to and including 1.26.2 use REVERSEPROXYTRUSTEDPROXIES= by default, allowing any source IP to impersonate a user when reverse-proxy authentication headers such as X-WEBAUTH-USER are enabled.

## Affected packages

- Go `code.gitea.io/gitea` < 1.26.3 → fixed: 1.26.3

## Affected products (CVE record)

- Gitea Gitea Open Source Git Server: <= 1.26.2

## Severity

- Gitea CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 2.76% probability of exploitation activity in the next 30 days; percentile 86.

## Sources

- [GitHub Security Advisory](https://github.com/go-gitea/gitea/security/advisories/GHSA-f75j-4cw6-rmx4)
- [GitHub Pull Request #38151](https://github.com/go-gitea/gitea/pull/38151)
- [Gitea v1.26.3 Release](https://github.com/go-gitea/gitea/releases/tag/v1.26.3)
- [Gitea v1.26.4 Release Blog Post](https://blog.gitea.com/release-of-1.26.3-and-1.26.4/)
- [GitHub Advisory GHSA-f75j-4cw6-rmx4](https://github.com/advisories/GHSA-f75j-4cw6-rmx4)
- [CVE.org record CVE-2026-20896](https://www.cve.org/CVERecord?id=CVE-2026-20896)
- [NVD entry CVE-2026-20896](https://nvd.nist.gov/vuln/detail/CVE-2026-20896)
- [github.com](https://github.com/go-gitea/gitea/commit/99f8b3d9a1d32f4c39828e07971455a18191e0b9)

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Source page: https://erroneo.us/security/cve/CVE-2026-20896/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt