XSS in Wwbn Avideo
CVE-2026-33500
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.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (15.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 16th percentile — 15.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.000
Affected products
- Wwbn Avideo — versions <= 26.0
Weakness classification (CWE)
References
- github.com/WWBN/AVideo/security/advisories/GHSA-72h5-39r7-r26j (Exploit, Mitigation, Vendor Advisory)
- github.com/WWBN/AVideo/commit/3ae02fa240939dbefc5949d64f05790fd25d728d (Patch)
Frequently asked questions
- What is CVE-2026-33500?
- CVE-2026-33500 is a medium-severity vulnerability in Wwbn Avideo, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-03-23.
- How severe is CVE-2026-33500?
- Medium severity. CVSS v3 base score is 5.4 out of 10.