CVE-2026-105240

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. 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.

5.3 /10

CVSS v3 : MEDIUM

V3 Legend

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References
Link Resource
https://github.com/apache/logging-log4net/commit/6046fe9d7f353b49fe995361c071ec2eea8f7ef6 Patch
https://github.com/apache/logging-log4net/pull/315 Patch
https://lists.apache.org/thread.html/gyw2d4ppy82t1vlpdknkfd1nmzp21z17 Mailing List Vendor Advisory
http://www.openwall.com/lists/oss-security/2026/10/07/18 Mailing List Third Party Advisory
Configurations

Configuration 1 (hide)

cpe:2.3:a:apache:log4net:*:*:*:*:*:*:*:*
History

09 Oct 2026, 15:41

Type Values Removed Values Added
First Time Apache log4net
Apache
CPE cpe:2.3:a:apache:log4net:*:*:*:*:*:*:*:*
References () https://github.com/apache/logging-log4net/commit/6046fe9d7f353b49fe995361c071ec2eea8f7ef6 - () https://github.com/apache/logging-log4net/commit/6046fe9d7f353b49fe995361c071ec2eea8f7ef6 - Patch
References () https://github.com/apache/logging-log4net/pull/315 - () https://github.com/apache/logging-log4net/pull/315 - Patch
References () https://lists.apache.org/thread.html/gyw2d4ppy82t1vlpdknkfd1nmzp21z17 - () https://lists.apache.org/thread.html/gyw2d4ppy82t1vlpdknkfd1nmzp21z17 - Mailing List, Vendor Advisory
References () http://www.openwall.com/lists/oss-security/2026/10/07/18 - () http://www.openwall.com/lists/oss-security/2026/10/07/18 - Mailing List, Third Party Advisory

07 Oct 2026, 07:16

Type Values Removed Values Added
References
  • () http://www.openwall.com/lists/oss-security/2026/10/07/18 -

06 Oct 2026, 20:17

Type Values Removed Values Added
New CVE
Information

Published : 2026-10-06 20:17

Updated : 2026-10-09 15:41

NVD link : CVE-2026-105240

Mitre link : CVE-2026-105240

CVE.ORG link : CVE-2026-105240

JSON object : View

Products Affected

apache

  • log4net
CWE
CWE-158

Improper Neutralization of Null Byte or NUL Character