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.
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.
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Affected Vendors & Products
Advisories
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Fixes
Solution
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Workaround
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References
History
Tue, 06 Oct 2026 20:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | Apache log4net: Oversize EventLogAppender record silently discarded | |
| Weaknesses | CWE-778 | |
| References |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: apache
Published:
Updated: 2026-10-06T19:51:25.116Z
Reserved: 2026-10-04T16:21:38.272Z
Link: CVE-2026-105243
No data.
Status : Received
Published: 2026-10-06T20:17:16.167
Modified: 2026-10-06T20:17:16.167
Link: CVE-2026-105243
No data.
OpenCVE Enrichment
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Weaknesses