CVE-2026-105240

Improper Neutralization of Null Byte or NUL Character vulnerability in the OutputDebugStringAppender of Apache log4net. A NUL character in logged content ended the debug output record at that point, so everything the layout rendered after it, including exception text and trailing fields, was silently lost. A party whose data reaches a log message could hide the rest of that record. Only applications on Windows that use OutputDebugStringAppender 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.

• CWE-158

• https://github.com/apache/logging-log4net/commit/6046fe9d7f353b49fe995361c071ec2eea8f7ef6Patch
• https://github.com/apache/logging-log4net/pull/315Patch
• https://lists.apache.org/thread.html/gyw2d4ppy82t1vlpdknkfd1nmzp21z17Mailing List, Vendor Advisory
• https://www.openwall.com/lists/oss-security/2026/10/07/18Mailing List, Third Party Advisory

Published

Oct 6, 2026

Last Modified

Oct 9, 2026

Status

Analyzed

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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