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
Affected Vendors & Products
References
History
Fri, 09 Oct 2026 15:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| CPEs | cpe:2.3:a:apache:log4net:*:*:*:*:*:*:*:* |
Thu, 08 Oct 2026 20:30:00 +0000
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|---|---|---|
| Metrics |
ssvc
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Wed, 07 Oct 2026 07:30:00 +0000
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| References |
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Wed, 07 Oct 2026 00:00:00 +0000
| Type | Values Removed | Values Added |
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| First Time appeared |
Apache
Apache log4net |
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| Vendors & Products |
Apache
Apache log4net |
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: 2026-10-06T19:51:25.116Z
Updated: 2026-10-07T14:49:41.976Z
Reserved: 2026-10-04T16:21:38.272Z
Link: CVE-2026-105243
Updated: 2026-10-07T06:11:59.799Z
Status : Analyzed
Published: 2026-10-06T20:17:16.167
Modified: 2026-10-09T15:26:03.430
Link: CVE-2026-105243
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