CVE-2026-105244
Received
Received - Intake
Improper Output Encoding in Apache log4net RemoteSyslogAppender
Vulnerability report for CVE-2026-105244, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-06
Last updated on: 2026-10-06
Assigner: Apache Software Foundation
Description
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.
CVSS Scores
EPSS Scores
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| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| Apache | Software | Foundation Apache log4net 1.2.12 |
| Apache | Software | Foundation Apache log4net 56a2e146e21ff4737e1ff3ec308810e667873947 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-116 | The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved. |
