Medium 5.3Published Oct 6, 2026

CVE-2026-105244Apache log4net: RemoteSyslogAppender silently deletes non-ASCII content

Updated under an hour ago (2026-10-19 08:23 UTC)

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It affects Apache Software Foundation Apache log4net and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Apache Software Foundation Apache log4net

Exploited in the last 30 days

Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net. Every character outside visible ASCII and space was removed from the record instead of being escaped, so non-ASCII text and control characters such as tabs disappeared without notice. A party whose data reaches a log message could make a distinct value look identical in the record, for example a user name holding a zero-width space logged as admin. Only applications that use RemoteSyslogAppender are affected. This issue affects Apache log4net: from 1.2.12 before 3.5.0. Users are recommended to upgrade to version 3.5.0, which fixes the issue.

CVSS: 5.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Weakness (CWE): CWE-116
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: apache
NVD analysis: Analyzed
Record last updated: Oct 7, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Apache Software Foundation Apache log4net apache_software_foundation:apache_log4net (from the name)	from 1.2.12 before 3.5.0	CNA record
apache log4net apache:log4net	from 1.2.12 before 3.5.0	NVD

References

https://github.com/apache/logging-log4net/pull/315patch, vendor-advisory
https://github.com/apache/logging-log4net/commit/77717061b20d4346b6c0ce6b54643d85fb348bc7patch
https://lists.apache.org/thread.html/q7649hhdodthoqw8jsjgtnb4m8qfy6d6vendor-advisory, mailing-list
http://www.openwall.com/lists/oss-security/2026/10/07/19mailing-list, third-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.