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CVE-2026-105242

Apache log4net: Request validation failure drops the event in the aspnet-request converter

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 3.5.0
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: yes
  • Technical impact: partial

Summary

Improper Handling of Exceptional Conditions vulnerability in the aspnet-request pattern converter of Apache log4net. Reading request parameters triggers ASP.NET request validation, so a request carrying content such as markup made the layout throw and the appender discarded the whole event. A sender could suppress the log record of their own request. Only applications on ASP.NET for .NET Framework whose layout uses %aspnet-request are affected. This issue affects Apache log4net: from 1.2.11 before 3.5.0. Users are recommended to upgrade to version 3.5.0, which fixes the issue.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: yes · Technical impact: partial

  3. Record last updated

Affected versions

  • log4net

    From 1.2.11 · fixed in 3.5.0

  • log4net

    From 243f1e9f3ee235955bade4b4fe664a903378719a · fixed in 145203420c579a703008b4b723b6a080757f4964

References 3

GitHub · apache/logging-log4net

lists.apache.org