CVE-2026-43939 Details
Description
YetAnotherForum.NET (YAF.NET) is a C# ASP.NET forum. Prior to 4.0.5 and 3.2.12, the thread posting and reply feature accepts user-supplied content via a a post or reply that is stored server-side and later rendered back into the thread page without adequate HTML sanitization or contextual output encoding. This vulnerability is fixed in 4.0.5 and 3.2.12.
A stored cross-site scripting vulnerability has been identified in YetAnotherForum.NET (YAF.NET) versions prior to 4.0.5 and 3.2.12. The issue arises in the thread posting and reply feature, which accepts user-generated content that is saved on the server and later displayed on the thread page without proper HTML sanitization or contextual output encoding. This flaw allows injected JavaScript to execute in the browsers of all users viewing the affected thread, including moderators and administrators.
Users can upgrade to YetAnotherForum.NET versions 4.0.5 or 3.2.12 to address this vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed May 12, 2026CISA-ADP
Assessed May 13, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/YAFNET/YAFNET/security/advisories/GHSA-8rq5-wwpp-fmj2 | CISA-ADP | AdvisoryExploitRemedyVendor |
| https://github.com/YAFNET/YAFNET/security/advisories/GHSA-8rq5-wwpp-fmj2 | [email protected] | AdvisoryExploitRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-116 | Improper Encoding or Escaping of Output | [email protected] |
| CWE-79 | Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') | [email protected] |
| CWE-80 | Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| YetAnotherForum.NET | 4.0.4 (semver) <= 3.2.11 (semver) |
CPE
Remediation
| |
Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| May 13, 2026 | CVE Modified | CISA-ADP |
| May 12, 2026 | New CVE Received | [email protected] |