Bug 2547138 (CVE-2026-105240) - CVE-2026-105240 log4net-windows: log4net: Log truncation via null byte injection in OutputDebugStringAppender
Summary: CVE-2026-105240 log4net-windows: log4net: Log truncation via null byte inject...
Keywords:
Status: NEW
Alias: CVE-2026-105240
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-10-06 20:02 UTC by OSIDB Bzimport
Modified: 2026-10-07 10:37 UTC (History)
0 users

Fixed In Version:
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Description OSIDB Bzimport 2026-10-06 20:02:43 UTC 
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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