CVE-2026-105239
mediumpriority · track · 0EPSS 0.008 · 57 %ileDEUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (3)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-3772Apache log4net: Mehrere Schwachstellen ermöglichen Manipulation von DateienDeutsch2026-10-06csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Apache log4net ausnutzen, um Dateien zu manipulieren.
sources
Which sources assert this record, and when.
references (4) nvd
External citations — patches, advisories, analysis.
- http://www.openwall.com/lists/oss-security/2026/10/07/14Mailing ListThird Party Advisory
- https://github.com/apache/logging-log4net/commit/dc5855a0720c91590fd7a81d729ea01fdd69e000Patch
- https://github.com/apache/logging-log4net/pull/315Patch
- https://lists.apache.org/thread.html/9fx1qo5hc0tg8ym0t6p9gt1zpb2qlxpqMailing ListVendor Advisory
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