Vulnerability in Apache Software Foundation Apache log4net

[ Description ]Official description

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.

[ Fixes ]Fixes and patches

• Patch on github.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD
• Patch on github.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD

[ Advisories ]Government CERT advisories

• BSI CERT-Bund6 Oct 2026WID-SEC-2026-3772

  Apache log4net: Multiple vulnerabilities allow file manipulation Translated from German

  CVE-2026-105240CVE-2026-105239CVE-2026-105243+3 more CVEs

[ References ]References

• github.com/apache/logging-log4net/commit/145203420c579a703008b4b723b6a080757f4964Patch
• github.com/apache/logging-log4net/pull/316Patch
• lists.apache.org/thread.html/zg6dbqm4ztm7j3c21nfsqj0yxm5yrpdxMailing ListVendor Advisory
• www.openwall.com/lists/oss-security/2026/10/07/16Mailing ListThird Party Advisory