CVE-2026-33500
AVideo Vulnerable to Stored XSS via Markdown `javascript:` URI Bypasses ParsedownSafeWithLinks Sanitization
WWBN AVideo is an open source video platform. In versions up to and including 26.0, 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. Commit 3ae02fa240939dbefc5949d64f05790fd25d728d contains a patch.
- Affected
- WWBN · AVideo
- CVSS v3.1 GITHUB
- 5.4 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - EPSS
- 0.26% chance of exploitation in the next 30 days, 16th percentile
- Published
- 2026-03-23
- Updated
- 2026-03-24
Proof-of-concept exploits (1)
Security advisories
- WWBN/AVideo/security/advisories/GHSA-72h5-39r7-r26j
- WWBN/AVideo/commit/3ae02fa240939dbefc5949d64f05790fd25d728d