CVE-2026-105243
Apache log4net: Oversize EventLogAppender record silently discarded
- State
- Published
- Severity
- 5.3 Medium
- Published
- Oct 6, 2026
- Updated
- Oct 7, 2026
- Reserved
- Oct 4, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 5.3 Medium | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N | apache |
Weaknesses
- CWE-778 Insufficient Logging
Affected Products
| Product | Versions |
|---|---|
Apache log4netApache Software Foundation |
|
Apache log4netApache Software Foundation |
|
References
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