Cross-Site Scripting (XSS) in wwbn/avideo (CVE-2026-33500)
Summary
Cross-site scripting in wwbn/avideo (CVE-2026-33500). Risk of unauthorized operations or information disclosure. Exploitable via ParsedownSafeWithLinks.
Original description
The description as published by the source.
Summary
The fix for CVE-2026-27568 (GHSA-rcqw-6466-3mv7) introduced a custom ParsedownSafeWithLinks class that sanitizes raw HTML and 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.
Details
The original fix (commit ade348ed6) enabled setSafeMode(true), which activated Parsedown's built-in URL scheme filtering. This was then replaced by commit f13587c59 with a custom approach that turned safeMode back off:
objects/functionsSecurity.php:442-446 — safeMode disabled:
function markDownToHTML($text) {
$parsedown = new ParsedownSafeWithLinks();
$parsedown->setSafeMode(false); // line 445 — disables Parsedown's built-in javascript: filtering
$parsedown->setMarkupEscaped(false);
$html = $parsedown->text($text);
ParsedownSafeWithLinks (lines 349-440) overrides blockMarkup() and inlineMarkup() to sanitize raw HTML `` tags via sanitizeATag(), which whitelist-checks the URL scheme:
// sanitizeATag() at line 360 — only allows http(s), mailto, /, #
if (preg_match('/^(…
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-33500 has been found in wwbn/avideo.
Attackers can target a specific entry point like ParsedownSafeWithLinks over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "wwbn/avideo CVE-2026-33500" on the vendor's site.
CVE-2026-33500 (wwbn/avideo) — CWE-79
Attack vector: remote (network-reachable)
Attack surface: ParsedownSafeWithLinks / safeMode / ade348ed6 / f13587c59
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Cross-site scripting (XSS) (CWE-79) exists in wwbn/avideo. Attackers reach the vulnerable code path via ParsedownSafeWithLinks.
Check the vendor advisory for the affected versions of wwbn/avideo. Attack surface: ParsedownSafeWithLinks / safeMode / ade348ed6 / f13587c59.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'wwbn/avideo' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'wwbn/avideo' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
wwbn/avideoを grep し、稼働しているサービス・バージョンを把握する。 -
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com