Vulnerability in YetAnotherForum.NET Affects User Input Handling
CVE-2026-43939

7.3HIGH

Key Information:

Vendor

Yafnet

Status
Yafnet
Vendor
CVE Published:
12 May 2026

What is CVE-2026-43939?

YetAnotherForum.NET (YAF.NET) is a C# ASP.NET-based forum that contains a vulnerability affecting its thread posting and reply functionalities. Specifically, user-supplied content is inadequately sanitized before being stored server-side and later rendered on thread pages. This lack of proper HTML sanitization or contextual output encoding may allow attackers to exploit this flaw, potentially leading to issues such as cross-site scripting (XSS). The vulnerability can be mitigated by updating to versions 4.0.5 or 3.2.12, where adequate input validation measures are implemented.

Affected Version(s)

YAFNET >= 4.0.0-beta.1, < 4.0.5 < 4.0.0-beta.1, 4.0.5

YAFNET < 3.2.12 < 3.2.12

References

https://github.com/YAFNET/YAFNET/security/advisories/GHSA...
x_refsource_CONFIRM

CVSS V3.1

Score:
7.3
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.