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.
Advisories

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Fixes

Solution

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Workaround

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History

Tue, 06 Oct 2026 20:00:00 +0000

Type Values Removed Values Added
Description 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.
Title Apache log4net: RemoteSyslogAppender silently deletes non-ASCII content
Weaknesses CWE-116
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: apache

Published:

Updated: 2026-10-06T19:52:31.116Z

Reserved: 2026-10-04T16:22:18.416Z

Link: CVE-2026-105244

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-06T20:17:16.297

Modified: 2026-10-06T20:17:16.297

Link: CVE-2026-105244

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses