CVE-2026-105242

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.

Score

CVSS 3.1 5.3 Medium

Status

Analyzed - security@apache.org

Published

2026-10-06

Last modified

2026-10-09

Weaknesses

CWE-755

Affected products

• Log4net (Apache)
• Apache Log4net (Apache Software Foundation)

References

• https://github.com/apache/logging-log4net/pull/316
• https://github.com/apache/logging-log4net/commit/145203420c579a703008b4b723b6a080757f4964
• https://lists.apache.org/thread.html/zg6dbqm4ztm7j3c21nfsqj0yxm5yrpdx
• http://www.openwall.com/lists/oss-security/2026/10/07/16