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.
History

Fri, 09 Oct 2026 16:00:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:apache:log4net:*:*:*:*:*:*:*:*

Thu, 08 Oct 2026 07:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 07 Oct 2026 07:30:00 +0000

Type Values Removed Values Added
References

Wed, 07 Oct 2026 02:15:00 +0000

Type Values Removed Values Added
First Time appeared Apache
Apache log4net
Vendors & Products Apache
Apache log4net

Tue, 06 Oct 2026 20:00:00 +0000

Type Values Removed Values Added
Description 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.
Title Apache log4net: NUL character truncates OutputDebugStringAppender records
Weaknesses CWE-158
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: apache

Published: 2026-10-06T19:47:44.900Z

Updated: 2026-10-07T16:27:16.989Z

Reserved: 2026-10-04T16:20:07.533Z

Link: CVE-2026-105240

cve-icon Vulnrichment

Updated: 2026-10-07T06:11:56.396Z

cve-icon NVD

Status : Analyzed

Published: 2026-10-06T20:17:15.777

Modified: 2026-10-09T15:41:47.250

Link: CVE-2026-105240

cve-icon Redhat

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