CVE-2026-35055 XenForo Cross-Site Scripting via Lightbox in Posts
Attackers can inject malicious scripts into XenForo posts that execute in victims' browsers when viewing lightbox content, potentially leading to session hijacking.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-35055?
CVE-2026-35055 is a medium-severity cross-site scripting vulnerability in XenForo, published on 1 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
XenForo before 2.3.9 and before 2.2.18 is vulnerable to cross-site scripting (XSS) related to lightbox usage in posts. An attacker can inject malicious scripts that execute when users interact with post content displayed in the lightbox.
Weakness: CWE-79
Which versions are affected by CVE-2026-35055?
It affects 1 product.
Products include Xenforo Xenforo.
How do I fix CVE-2026-35055?
No fix has been published for CVE-2026-35055 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-35055 being exploited?
There is no known exploitation of CVE-2026-35055 in the wild and no public exploit code.
Other vulnerabilities in XenForo
- CVE-2025-71279 XenForo Passkey Security Bypass
- CVE-2026-73309 XenForo < 2.3.13 Authentication Bypass via OAuth2 Token Endpoint
- CVE-2026-73311 XenForo < 2.3.13 OAuth2 Authorization Code Reuse
- CVE-2026-73312 XenForo < 2.3.13 Refresh Token Replay via Expired Access Token
- CVE-2024-38457 Xenforo before 2.2.16 allows CSRF.
Sources
Also known as GHSA-7285-3w46-g6m6.