Is CVE-2026-43939 actively exploited?

No active exploitation of CVE-2026-43939 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-43939 be exploited remotely?

Yes. CVE-2026-43939 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-43939?

CVE-2026-43939 has a CVSS score of 7.3 (HIGH).

HOME VULNERABILITIESCVE-2026-43939

HIGH

CVE-2026-43939

CWE-79Published: May 12, 2026· Updated: May 13, 2026

7.3

CVSS v3.1

EPSS:0.03%probability of exploitation in 30 daysPercentile:9.5th

Official 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.

NVD Source

Technical Analysis

CVE-2026-43939 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), with a CVSS base score of 7.3.

From a weakness classification perspective (CWE-79): Cross-site scripting (XSS) vulnerabilities allow attackers to inject malicious scripts into web pages viewed by other users.