Disclosure summary
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.
Source-reported weakness categories
CWE-116
Source-specific records & product guidance
Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.
NIST National Vulnerability Database · NVD-CVE-2026-105244
Open original source · Updated Oct 09, 2026
Only CPE matches marked vulnerable=true are indexed. AND/OR platform conditions must be checked in the original NVD record.
| Vendor | Product / association | Version / bounds |
|---|---|---|
| apache | log4net | * {"versionStartIncluding":"1.2.12","versionEndExcluding":"3.5.0"} |
Original records & references
- NIST NVD record
- CVE Program record
- github.com — Patch
- github.com — Patch, Vendor Advisory
- lists.apache.org — Mailing List, Vendor Advisory
PUBLISHED 2026-10-06T16:17:16-04:00
MODIFIED 2026-10-09T11:18:44-04:00
INGESTED 2026-10-10T20:50:46-04:00