CVE-2026-50190
Received Received - Intake

Stored XSS in Shaarli Bookmarking Service

Publication date: 2026-08-20

Last updated on: 2026-08-20

Assigner: GitHub, Inc.

Description
Shaarli is a personal bookmarking service. Versions prior to 0.16.3 are vulnerable to stored XSS in `application/front/controller/visitor/BookmarkListController.php`. The `permalink` handler concatenates the raw `$bookmark->getTitle()` into the `pagetitle` template variable and the RainTPL template emits it into the document `<title>` element without HTML escaping. A bookmark title containing `</title><script>...</script>` closes the document title early and the injected script executes in the Shaarli origin for any visitor of `/shaare/{hash}`. Shaarli's metadata fetcher copies a remote page's `<title>` text verbatim into the local bookmark title, so an attacker who hosts an attacker-controlled URL and convinces an administrator to bookmark it plants the payload with no further interaction — and the resulting permalink fires for every visitor including the administrator on first save, providing a one-shot administrator account takeover. Version 0.16.3 fixes the issue.

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Meta Information

Published
2026-08-20
Last Modified
2026-08-20
Generated
2026-08-20
AI Q&A
2026-08-20
EPSS Evaluated
N/A
NVD
CVE-2026-50190
EUVD
EUVD-2026-63551

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
shaarli shaarli to 0.16.1 (exc)
shaarli shaarli to 0.16.3 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 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.

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Executive Summary

This is a stored cross-site scripting (XSS) vulnerability in Shaarli versions before 0.16.3. It occurs in the permalink handler where a bookmark title is inserted into the document title without HTML escaping. An attacker can craft a title containing malicious JavaScript that executes when the page is viewed by others.

Detection Guidance

Check Shaarli versions prior to 0.16.3 for stored XSS in bookmark titles. Inspect bookmark titles containing script tags or unusual characters like </title><script>. Review server logs for suspicious bookmark creation events or unauthorized actions.

Impact Analysis

An attacker could steal session cookies, perform administrative actions, or take over an administrator's account. The attack can be automated by tricking an admin into bookmarking a malicious URL, which then executes the payload for all visitors.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, potentially violating GDPR's confidentiality and integrity requirements. For HIPAA, it may expose protected health information if bookmarks contain or link to such data.

Mitigation Strategies

Upgrade Shaarli to version 0.16.3 or later. Apply HTML escaping to bookmark titles before rendering. Sanitize titles from metadata fetcher to prevent malicious script injection. Remove any suspicious bookmarks created by untrusted sources.

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