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OpenAdvisories
High · 7.3 CVE-2026-43939 EUVD-2026-29481GHSA-8rq5-wwpp-fmj2

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

Published May 12, 2026 · Updated May 13, 2026 · Assigned by GitHub_M

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.

Affected products

VendorProductAffectedFixed
YAFNET YAFNET >= 4.0.0-beta.1, < 4.0.5, < 3.2.12 —

Affected packages

EcosystemPackageAffectedFixedRecord
NuGet YAFNET.Core >= 4.0.0-beta01, < 4.0.5 4.0.5 GHSA-8rq5-wwpp-fmj2
NuGet YAFNET.Core < 3.2.12 3.2.12 GHSA-8rq5-wwpp-fmj2

References