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Possible XSS via redir parameter when using subrequest auth mode

Low
Xe published GHSA-cf57-c578-7jvv Oct 30, 2025

Package

docker ghcr.io/techarohq/anubis (Docker)

Affected versions

< 1.23.0

Patched versions

1.23.0
gomod github.com/TecharoHQ/anubis (Go)
< 1.23.0
1.23.0

Description

Summary

When using subrequest authentication, Anubis did not perform validation of the redirect URL and redirects user to any URL scheme. While most modern browsers do not allow a redirect to javascript: URLs, it could still trigger dangerous behavior in some cases.

GET https://example.com/.within.website/?redir=javascript:alert() responds with Location: javascript:alert().

Impact

Anybody with a subrequest authentication seems affected. Using javascript: URLs will probably be blocked by most modern browsers, but using custom protocols for third-party applications might still trigger dangerous operations.

Note

This was originally reported by @mbiesiad against Weblate.

This was originally reported a month ago and I missed it because work has been wiping me out emotionally. This is not the experience I want security researchers to have and I am sorry it took so long to resolve this.

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N

CVE ID

No known CVE

Weaknesses

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Learn more on MITRE.

URL Redirection to Untrusted Site ('Open Redirect')

A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks. Learn more on MITRE.

Credits