vulnerability / NVI-00001836 / Revision 1
YOURLS is vulnerable to XSS through JSONP and Callback request parameters
OSV carries this publisher advisory for yourls/yourls. This is an aggregated source copy; consult the original publisher and compare update dates.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
yourls/yourls
source listedECOSYSTEM: introduced 0; last_affected 1.10.2
### 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","callb
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-6mp4-q625-mxjp ↗
GitHub Advisory Database via OSV · vendor advisory
Observed . GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.