Advisory severityMedium5.3Apache Software Foundation Updated

Medium [CVE-2026-105244] Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net

This medium-severity Apache Software Foundation advisory covers CVE-2026-105244; related products: Apache log4net.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-105244 Source published Oct 6, 2026Source updated Oct 7, 2026

VulniPulse record published Oct 6, 2026Record updated Oct 7, 2026

CVE-2026-105244

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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.

Affected versions

1.2.12 before 3.5.0

Official advisory · high-confidence parse· fetched 1 day ago·verify at source

Fixed versions

3.5.0

Official advisory · high-confidence parse· fetched 1 day ago·verify at source

Mitigation checklist

Recommended fix / mitigation

Users are recommended to upgrade to version 3.5.0, which fixes the issue.

Official advisory · high-confidence parse· fetched 1 day ago·verify at source

Sources

Official and corroborating records used to build this advisory.

Official vendor advisoryofficial
Official advisory page fetched and parsed; accepted detail fields are attributed to this page.
Apache Software Foundation
CVE.org CNA recordCVE.org
Independent CNA record used for near-real-time discovery and missed-CVE reconciliation. Discovered from the machine-readable feed https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/delta.json; this link opens the CVE.org record for CVE-2026-105244 instead of the raw feed document.
CVE Program

Cross-references

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CVE-2026-105244NVD CVE.org MITRE

Official resources

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Official documentation
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Apache project downloads (fixed releases)
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