CVE-2026-43939
YAF.NET: Stored XSS in Forum Thread Posts/Replies Allowing Arbitrary JavaScript Execution for All Thread Viewers
CVSS Score
7.3
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-79 CWE-80 CWE-116 |
| Vendor | yafnet |
| Product | yafnet |
| Published | May 12, 2026 |
| Last Updated | May 13, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None
Affected Versions
YAFNET / YAFNET
>= 4.0.0-beta.1, < 4.0.5 < 3.2.12