Insufficient Logging Affecting log4net package, versions *
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIAN13-LOG4NET-20562063
- published7 Oct 2026
- disclosed6 Oct 2026
Introduced: 6 Oct 2026
NewCVE-2026-105243 (opens in a new tab)How to fix?
There is no fixed version for Debian:13 log4net.
NVD Description
Note: Versions mentioned in the description apply only to the upstream log4net package and not the log4net package as distributed by Debian.
See How to fix? for Debian:13 relevant fixed versions and status.
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.
References
- https://security-tracker.debian.org/tracker/CVE-2026-105243
- https://github.com/apache/logging-log4net/commit/28fbfb25678c48a8cc5bc9b94ead0dddfc39ffed
- https://github.com/apache/logging-log4net/pull/315
- https://lists.apache.org/thread.html/jr6fj5skv1vnjbc9jmt8bp151p8ow1rp
- http://www.openwall.com/lists/oss-security/2026/10/07/17