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XSS in https://fed.brid.gy/

Moderate
snarfed published GHSA-3m75-xhjm-8h36 Jun 13, 2025

Package

bridgy-fed

Affected versions

< 20250613t075049

Patched versions

20250613t075049

Description

Summary

fed.brid.gy's search is vulnerable to XSS.

Details

It looks like the fed.brid.gy code implicitly trusts the value of 'id' in several places and includes in as part of rendering responses:

https://github.com/search?q=repo%3Asnarfed%2Fbridgy-fed%20Couldn%27t%20determine%20network&type=code

PoC

$ curl 'https://fed.brid.gy/user-page' --data-raw 'id=%3Cscript%3Ealert%281%29%3C%2Fscript%3E' | grep alert
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 3052 100 3010 100 42 9477 132 --:--:-- --:--:-- --:--:-- 9627

Couldn't determine network for <script>alert(1)</script>.

Impact

Getting someone to click on a link which results in a malicious POST to https://fed.brid.gy/user-page will result in JavaScript being executed in the context of fed.brid.gy.

Severity

Moderate

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
Required
Scope
Changed
Confidentiality
None
Integrity
Low
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:R/S:C/C:N/I:L/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.

Credits