{"id":"CVE-2026-33500","state":"PUBLISHED","title":"AVideo Vulnerable to Stored XSS via Markdown `javascript:` URI Bypasses ParsedownSafeWithLinks Sanitization","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.","publishedAt":"2026-03-23T16:24:52.892Z","updatedAt":"2026-03-24T17:39:33.796Z","severity":{"score":5.4,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["WWBN AVideo"],"affected":[{"vendor":"WWBN","product":"AVideo","versions":[{"version":"<= 26.0","status":"affected"}]}],"references":["https://github.com/WWBN/AVideo/security/advisories/GHSA-72h5-39r7-r26j","https://github.com/WWBN/AVideo/commit/3ae02fa240939dbefc5949d64f05790fd25d728d"],"weaknesses":["CWE-79"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/33xxx/CVE-2026-33500.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-33500","state":"PUBLISHED","datePublished":"2026-03-23T16:24:52.892Z","dateUpdated":"2026-03-24T17:39:33.796Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-03-20T16:59:08.888Z"},"containers":{"cna":{"title":"AVideo Vulnerable to Stored XSS via Markdown `javascript:` URI Bypasses ParsedownSafeWithLinks Sanitization","descriptions":[{"lang":"en","value":"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":[{"vendor":"WWBN","product":"AVideo","versions":[{"version":"<= 26.0","status":"affected"}]}],"references":[{"url":"https://github.com/WWBN/AVideo/security/advisories/GHSA-72h5-39r7-r26j","name":"https://github.com/WWBN/AVideo/security/advisories/GHSA-72h5-39r7-r26j","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/WWBN/AVideo/commit/3ae02fa240939dbefc5949d64f05790fd25d728d","name":"https://github.com/WWBN/AVideo/commit/3ae02fa240939dbefc5949d64f05790fd25d728d","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.4,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"LOW","scope":"CHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-79","lang":"en","description":"CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-03-23T16:24:52.892Z"},"source":{"advisory":"GHSA-72h5-39r7-r26j","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-03-24T17:38:19.380717Z","id":"CVE-2026-33500","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-03-24T17:39:33.796Z"}}]}}}