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CVE-2026-105243 Details

Description

Insufficient Logging vulnerability in the EventLogAppender of Apache log4net. Long messages were truncated to a fixed size that exceeds what the Windows Event Log accepts once the log and source names are counted, and the event log then stored nothing and reported nothing. A party whose data reaches a log message could suppress the whole record by making it long enough. 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.

Metrics

CVSS 3.x Severity and Vector Strings:

CNA: [email protected]CVSS-B:5.3 MEDIUMVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
http://www.openwall.com/lists/oss-security/2026/10/07/17	CVE
https://github.com/apache/logging-log4net/commit/28fbfb25678c48a8cc5bc9b94ead0dddfc39ffed	[email protected]
https://github.com/apache/logging-log4net/pull/315	[email protected]
https://lists.apache.org/thread.html/jr6fj5skv1vnjbc9jmt8bp151p8ow1rp	[email protected]

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-778	Insufficient Logging	[email protected]

Affected Products

No affected product data is available for this CVE.

Change History

3 change records found show changes

Date	Action	Recorded By
Oct 7, 2026	CVE Modified	CISA-ADP
Oct 7, 2026	CVE Modified	CVE
Oct 6, 2026	New CVE Received	[email protected]