Vulnerability · Published Aug 19, 2026 · Assigned by Fluid Attacks
CVE-2026-18430HumHub 1.18.4 - Stored XSS in comment-deletion notifications through unescaped administrator reason
High 7.2
In plain English
A high-severity cross-site scripting in HumHub from HumHub. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities).
Severity (CVSS 4.0)7.2High
Exploit odds (30 days)0.5%top 59.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official description
HumHub 1.18.4 contains a stored cross-site scripting vulnerability in the comment-deletion notification flow. A Space administrator can delete another user's comment, choose to notify the original author, and place HTML/JavaScript in the deletion reason.
Affected products (as reported)
Weakness: CWE-79 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N
References
- https://fluidattacks.com/es/advisories/personajes third-party-advisory
- https://github.com/humhub/humhub/pull/8365 patch
- https://github.com/humhub/humhub product