Vulnerability · Published Mar 23, 2026 · Assigned by GitHub_M

CVE-2026-33500AVideo Vulnerable to Stored XSS via Markdown `javascript:` URI Bypasses ParsedownSafeWithLinks Sanitization

Medium 5.4

In plain English

A medium-severity cross-site scripting in AVideo from WWBN. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 13% of all known vulnerabilities).

Severity (CVSS 3.1)5.4Medium

Exploit odds (30 days)0.2%top 86.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Packagist	wwbn/avideo	no fix listed	GHSA-72h5-39r7-r26j

Affected products (as reported)

Vendor	Product	Versions
WWBN	AVideo	<= 26.0

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

References

https://github.com/WWBN/AVideo/security/advisories/GHSA-72h5-39r7-r26j x_refsource_CONFIRM
https://github.com/WWBN/AVideo/commit/3ae02fa240939dbefc5949d64f05790fd25d728d x_refsource_MISC