Shaarli up to 0.16.1 Markdown Parser BookmarkMarkdownFormatter.php filterProtocols cross site scripting

Summaryinfo

A vulnerability was found in Shaarli up to 0.16.1. It has been declared as problematic. The impacted element is the function filterProtocols of the file BookmarkMarkdownFormatter.php of the component Markdown Parser. The manipulation results in cross site scripting. This vulnerability is identified as CVE-2026-48822. The attack can be executed remotely. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Shaarli up to 0.16.1. Affected is the function filterProtocols of the file BookmarkMarkdownFormatter.php of the component Markdown Parser. The manipulation with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as 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. This is going to have an impact on integrity. CVE summarizes:

Shaarli is a personal bookmarking service. Versions 0.16.1 and prior contain a stored Cross-Site Scripting (XSS) vulnerability in the Markdown-to-HTML conversion process used in the Bookmark Description field. An authenticated user can inject a malicious javascript: URI inside a Markdown link. The vulnerability originates in the filterProtocols method within BookmarkMarkdownFormatter.php.This method attempts to sanitize Markdown links by filtering dangerous protocols (such as javascript:) before rendering. It uses the following regular expression: (#]\((.*?)\)#is). This regex is designed to detect inline Markdown links, but it fails to detect Markdown reference-style links because reference-style links are resolved by the Markdown parser after preprocessing. The filterProtocols method never inspects the actual URL used in these references and as a result, an attacker can supply a javascript: URI inside a reference definition. This issue has been fixed in version 0.16.2.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-48822 since 05/22/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation needs additional levels of successful authentication. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1059.007 by the MITRE ATT&CK project.

By approaching the search of inurl:BookmarkMarkdownFormatter.php it is possible to find vulnerable targets with Google Hacking.

Upgrading to version 0.16.2 eliminates this vulnerability. The upgrade is hosted for download at github.com.

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Productinfo

Name

• Shaarli

Version

• 0.16.0
• 0.16.1

Website

• Product: https://github.com/shaarli/Shaarli/

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