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Anubis vulnerable to possible XSS via redir parameter when using subrequest auth mode

Low severity GitHub Reviewed Published Oct 30, 2025 in TecharoHQ/anubis

Package

gomod github.com/TecharoHQ/anubis (Go)

Affected versions

< 1.23.0

Patched versions

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.

References

@Xe Xe published to TecharoHQ/anubis Oct 30, 2025
Published to the GitHub Advisory Database Oct 30, 2025
Reviewed Oct 30, 2025

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

EPSS score

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.

CVE ID

No known CVE

GHSA ID

GHSA-cf57-c578-7jvv

Source code

Credits

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