Vulnerability in Apache Software Foundation Apache log4net

[ Description ]Official description

Improper Neutralization of Null Byte or NUL Character vulnerability in the EventLogAppender of Apache log4net. A NUL character in logged content ended the Windows Event Log record at that point, so everything the layout rendered after it, including exception text and trailing fields, was silently not stored. A party whose data reaches a log message could hide the rest of that record. Only applications on Windows that use EventLogAppender are affected. This issue affects Apache log4net: from 1.2.9 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/dc5855a0720c91590fd7a81d729ea01fdd69e000Patch
• github.com/apache/logging-log4net/pull/315Patch
• lists.apache.org/thread.html/9fx1qo5hc0tg8ym0t6p9gt1zpb2qlxpqMailing ListVendor Advisory
• www.openwall.com/lists/oss-security/2026/10/07/14Mailing ListThird Party Advisory