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.
Published: 2026-05-12
Score: 7.3 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-8rq5-wwpp-fmj2 YAFNET has Stored XSS in Forum Thread Posts/Replies that Allows Arbitrary JavaScript Execution for All Thread Viewers
History

Wed, 13 May 2026 15:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Wed, 13 May 2026 11:00:00 +0000

Type Values Removed Values Added
First Time appeared Yafnet
Yafnet yafnet
Vendors & Products Yafnet
Yafnet yafnet

Tue, 12 May 2026 15:00:00 +0000

Type Values Removed Values Added
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.
Title YAF.NET: Stored XSS in Forum Thread Posts/Replies Allowing Arbitrary JavaScript Execution for All Thread Viewers
Weaknesses CWE-116
CWE-79
CWE-80
References
Metrics cvssV3_1

{'score': 7.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-13T14:38:25.692Z

Reserved: 2026-05-04T16:59:09.089Z

Link: CVE-2026-43939

cve-icon Vulnrichment

Updated: 2026-05-13T14:33:10.309Z

cve-icon NVD

Status : Deferred

Published: 2026-05-12T15:16:15.647

Modified: 2026-05-13T18:24:58.737

Link: CVE-2026-43939

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-13T10:38:52Z

Weaknesses