๐Ÿ” CVE Alert

CVE-2026-105240

MEDIUM 5.3

Apache log4net: NUL character truncates OutputDebugStringAppender records

CVSS Score
5.3
EPSS Score
0.0%
EPSS Percentile
0th

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.

CWE CWE-158
Vendor apache software foundation
Product apache log4net
Published Oct 6, 2026
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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

Affected Versions

Apache Software Foundation / Apache log4net
1.2.9 < 3.5.0
Apache Software Foundation / Apache log4net
02e1e115435888485f2e28b414d267e39e799e07 < 6046fe9d7f353b49fe995361c071ec2eea8f7ef6

References

NVD โ†— CVE.org โ†— EPSS Data โ†—
github.com: https://github.com/apache/logging-log4net/pull/315 github.com: https://github.com/apache/logging-log4net/commit/6046fe9d7f353b49fe995361c071ec2eea8f7ef6 lists.apache.org: https://lists.apache.org/thread.html/gyw2d4ppy82t1vlpdknkfd1nmzp21z17

Credits

The Apache Software Foundation Claude Security Jan Friedrich