CVE-2026-35057: XenForo Stored Cross-Site Scripting via Structured Text Mentions

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-01 · updated 2026-06-17
Weakness: CWE-79

Description

XenForo before 2.3.10 and before 2.2.19 is vulnerable to stored cross-site scripting (XSS) in structured text mentions, primarily affecting legacy profile post content. An attacker can inject malicious scripts through crafted mentions that are stored and executed when other users view the content.

Affected products

XenForo: before 2.2.19; from 2.3.0 before 2.3.10 — fixed in 2.2.19, 2.3.10

How to fix

Upgrade to a fixed version: XenForo 2.2.19, 2.3.10. Check the vendor advisory for mitigations.

References

https://github.com/methosiea/xenforo-2-xss
https://xenforo.com/community/threads/xenforo-2-3-10-add-ons-and-2-2-19-released-includes-security-fix.236249/

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