CVE-2026-105239

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2026-105239
Improper Neutralization of Null Byte or NUL Character vulnerability in the EventLogAppender of Apache log4net. A NUL character in logged content ended the Windows Event Log record at that point, so everything the layout rendered after it, including exception text and trailing fields, was silently not stored. A party whose data reaches a log message could hide the rest of that record. Only applications on Windows that use EventLogAppender 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/dc5855a0720c91590fd7a81d729ea01fdd69e000 Patch
https://github.com/apache/logging-log4net/pull/315 Patch
https://lists.apache.org/thread.html/9fx1qo5hc0tg8ym0t6p9gt1zpb2qlxpq Mailing List Vendor Advisory
http://www.openwall.com/lists/oss-security/2026/10/07/14 Mailing List Third Party Advisory
Configurations

Configuration 1 (hide)

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

09 Oct 2026, 15:44

Type Values Removed Values Added
First Time Apache log4net
Apache
References () https://github.com/apache/logging-log4net/commit/dc5855a0720c91590fd7a81d729ea01fdd69e000 - () https://github.com/apache/logging-log4net/commit/dc5855a0720c91590fd7a81d729ea01fdd69e000 - 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/9fx1qo5hc0tg8ym0t6p9gt1zpb2qlxpq - () https://lists.apache.org/thread.html/9fx1qo5hc0tg8ym0t6p9gt1zpb2qlxpq - Mailing List, Vendor Advisory
References () http://www.openwall.com/lists/oss-security/2026/10/07/14 - () http://www.openwall.com/lists/oss-security/2026/10/07/14 - Mailing List, Third Party Advisory
CPE cpe:2.3:a:apache:log4net:*:*:*:*:*:*:*:*

07 Oct 2026, 07:16

Type Values Removed Values Added
References
  • () http://www.openwall.com/lists/oss-security/2026/10/07/14 -

06 Oct 2026, 20:17

Type Values Removed Values Added
New CVE
Information

Published : 2026-10-06 20:17

Updated : 2026-10-09 15:44

NVD link : CVE-2026-105239

Mitre link : CVE-2026-105239

CVE.ORG link : CVE-2026-105239

JSON object : View

Products Affected

apache

  • log4net
CWE
CWE-158

Improper Neutralization of Null Byte or NUL Character