CVE-2026-48822
Description
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.
Summary dbcve.org
Shaarli versions 0.16.1 and prior contain a stored XSS vulnerability in the Markdown-to-HTML conversion for Bookmark Descriptions. The filterProtocols method uses a regex that only detects inline Markdown links but fails to sanitize reference-style links, allowing attackers to inject malicious javascript: URIs that execute after Markdown parsing.
Mitigation
Upgrade to Shaarli version 0.16.2 or later, which contains the patched filterProtocols method that properly sanitizes both inline and reference-style Markdown links.