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Vulnerabilities

Vulnerability · CVE-2026-43939

YetAnotherForum.NET (YAF.NET) is a C# ASP.NET forum.

Published May 12, 2026 · catalog updated Jun 17, 2026 · YetAnotherForum.NET (YAF.NET) is a

Check if you run it

No confirmed exploitation is on record for CVE-2026-43939. EPSS is 0.35%. Act only if a listed version of YetAnotherForum.NET (YAF.NET) is a is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (YetAnotherForum.NET (YAF.NET) is a).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.35%
Remediation
Advisory link
Affected products
See sources for product scope

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.

No affected version ranges are stored yet. Use the vendor advisory before you decide this record does not apply.

How to fix CVE-2026-43939

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-43939. EPSS is 0.35%. Act only if a listed version of YetAnotherForum.NET (YAF.NET) is a is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-116; CWE-79: Cross-site Scripting (XSS); CWE-80: Basic XSS. EPSS 0.35%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 12, 2026 · NIST NVD

    Detected

    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.

  2. Jun 17, 2026 · NIST NVD

    Updated

    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.

Sources

  • CVE.orgVulnerability recordCVE-2026-43939

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-43939

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-2026-43939

    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 c

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.