CVE-2026-105244
mediumImproper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net.
Vendor / product: Apache — log4net
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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Affected products
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
References
- https://github.com/apache/logging-log4net/commit/77717061b20d4346b6c0ce6b54643d85fb348bc7 security@apache.org
- https://github.com/apache/logging-log4net/pull/315 security@apache.org
- https://lists.apache.org/thread.html/q7649hhdodthoqw8jsjgtnb4m8qfy6d6 security@apache.org
- http://www.openwall.com/lists/oss-security/2026/10/07/19 af854a3a-2127-422b-91ae-364da2661108