CVE-2026-43939 HIGH

CVE-2026-43939: YAF.NET: Stored XSS in Forum Thread Posts/Replies Allowing Arbitrary JavaScript Execution for All Thread Viewers

Vendor Yafnet
Product YAFNET
Weakness CWE-79 · XSS
Published May 12, 2026
Last update May 13, 2026
View on NVD All CVEs

CVSS base score

7.3/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction Required
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N

What the vulnerability does

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.

Key dates

Disclosure timeline

May 12, 2026 CVE published
May 13, 2026 Record updated