Gitea Docker image: REVERSE_PROXY_TRUSTED_PROXIES = * default lets any source IP impersonate any user via X-WEBAUTH-USER

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-20896: 2.76% estimated exploitation activity in the next 30 days; percentile 86.26 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The Gitea Docker images ship an app.ini template that hard-codes: The documented default for this setting, in custom/conf/app.example.ini, is 127.0.0.0/8,::1/128, i.e. only loopback is trusted. When an admin enables ENABLEREVERSEPROXYAUTHENTICATION = true to put Gitea behind an authenticating reverse proxy and leaves the trusted-proxies setting at "the default", they expect only the proxy's loopback connection to inject identity. The Docker image instead trusts X-WEBAUTH-USER from any source IP that can reach the container. Affected - gitea/gitea Docker images (verified 1.26.2) - docker/root/etc/templates/app.ini:55 - docker/rootless/etc/templates/app.ini:52 Binary distribution and self-built deployments that follow app.example.ini get the loopback-only default and are not affected. Reproduction Output: <titlealice - Dashboard - Gitea: Git with a cup of tea</title — attacker is logged in as alice with one header, no password, no cookie. Same payload with X-WEBAUTH-USER:…

Published by the source

21 Jul 2026, 20:28 UTC

Last modified by the source

21 Jul 2026, 20:28 UTC

Source last checked

26 Oct 2026, 15:27 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-f75j-4cw6-rmx4

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# Patch Next advisory brief: CVE-2026-20896

Advisory: Gitea Docker image: `REVERSE_PROXY_TRUSTED_PROXIES = *` default lets any source IP impersonate any user via `X-WEBAUTH-USER`
IDs: CVE-2026-20896, GHSA-f75j-4cw6-rmx4
Record: https://patchnext.com/advisories/cve-2026-20896 (revision 1, source checked 26 Oct 2026, 15:27 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: code.gitea.io/gitea 1.26.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go code.gitea.io/gitea: affected < 1.26.3; fixed in 1.26.3

## Suggested inspection (read-only)
- Go code.gitea.io/gitea: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on code.gitea.io/gitea.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-f75j-4cw6-rmx4 (GitHub-reviewed advisory GHSA-f75j-4cw6-rmx4 lists affected ranges: Go code.gitea.io/gitea >=0 <1.26.3)

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