CVE-2026-105242: Apache LOG4NET

Medium severity, CVSS 5.3. EPSS: 0.8% chance of exploitation in the next 30 days.

Improper Handling of Exceptional Conditions vulnerability in the aspnet-request pattern converter of Apache log4net. Reading request parameters triggers ASP.NET request validation, so a request carrying content such as markup made the layout throw and the appender discarded the whole event. A sender could suppress the log record of their own request. Only applications on ASP.NET for .NET Framework whose layout uses %aspnet-request are affected. This issue affects Apache log4net: from 1.2.11 before 3.5.0. Users are recommended to upgrade to version 3.5.0, which fixes the issue.

Affected products

• Apache LOG4NET: from 1.2.11, before 3.5.0 (fixed in 3.5.0)

Published 2026-10-06. Last modified 2026-10-09.