CVE-2026-105243

published 2026-10-06

CVE-2026-105243: Insufficient Logging vulnerability in the EventLogAppender of Apache log4net. Long messages were truncated to a fixed size that exceeds what the Windows Event…

Priority P4 31 medium 5.3 CVSS 3.1

AV N AC L PR N UI N S U C N I L A N

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.

Affected

3 ranges

Vendor	Product	Version range	Fixed in
apache	log4net	>= 1.2.9 < 3.5.0	3.5.0
apache_software_foundation	apache_log4net	>= 02e1e115435888485f2e28b414d267e39e799e07 < 28fbfb25678c48a8cc5bc9b94ead0dddfc39ffed	28fbfb25678c48a8cc5bc9b94ead0dddfc39ffed
apache_software_foundation	apache_log4net	>= 1.2.9 < 3.5.0	3.5.0

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