🚨 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.
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GitHub
escape NUL characters in OutputDebugStringAppender content #315 · apache/logging-log4net@6046fe9
OutputDebugStringW takes a null terminated string, so a NUL in logged content
ended the record there and dropped whatever the layout rendered after it.
The escape LocalSyslogAppender already had i...
October 9, 2026 14 1
