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  5. CVE-2026-33500

CVE-2026-33500: AVideo - Incomplete Fix for CVE-2026-27568: Stored XSS via Markdown `javascript:` URI Bypasses ParsedownSafeWithLinks Sanitization

March 20, 2026 (updated March 25, 2026)

The fix for CVE-2026-27568 (GHSA-rcqw-6466-3mv7) introduced a custom ParsedownSafeWithLinks class that sanitizes raw HTML <a> and <img> tags in comments, but explicitly disables Parsedown’s safeMode. This creates a bypass: markdown link syntax [text](javascript:alert(1)) is processed by Parsedown’s inlineLink() method, which does not go through the custom sanitizeATag() sanitization (that only handles raw HTML tags). With safeMode disabled, Parsedown’s built-in javascript: URI filtering (sanitiseElement()/filterUnsafeUrlInAttribute()) is also inactive. An attacker can inject stored XSS via comment markdown links.

References

  • github.com/WWBN/AVideo
  • github.com/WWBN/AVideo/commit/3ae02fa240939dbefc5949d64f05790fd25d728d
  • github.com/WWBN/AVideo/security/advisories/GHSA-72h5-39r7-r26j
  • github.com/advisories/GHSA-72h5-39r7-r26j
  • nvd.nist.gov/vuln/detail/CVE-2026-33500

Code Behaviors & Features

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Affected versions

All versions up to 26.0

Solution

Unfortunately, there is no solution available yet.

Impact 5.4 MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Learn more about CVSS

Weakness

  • CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Source file

packagist/wwbn/avideo/CVE-2026-33500.yml

Spotted a mistake? Edit the file on GitLab.

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