CVE-2026-73319

Summary

XenForo before 2.3.13 contains a cross-site scripting vulnerability in the dynamic redirect handler that allows unauthenticated attackers to execute arbitrary JavaScript in the board origin by crafting a malicious javascript: URI that bypasses host validation. Attackers can embed the board hostname in the URI authority component and use percent-encoded newlines to evade server-side filters, causing authenticated users who perform a Follow action to execute attacker-supplied JavaScript in their browser.

Affected Software

Weaknesses

• CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

References

• https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-gallery-versions-2-2-0-2-3-12.239856/
• https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-security-fixes.239857/
• https://bombobombone.github.io/posts/cve-2026-73319/
• https://github.com/BomboBombone/CVE-2026-73319
• https://www.vulncheck.com/advisories/xenforo-xss-via-dynamic-redirect-handler

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