CVE-2026-105239

Summary

Improper Neutralization of Null Byte or NUL Character vulnerability in the EventLogAppender of Apache log4net.

A NUL character in logged content ended the Windows Event Log record at that point, so everything the layout rendered after it, including exception text and trailing fields, was silently not stored. A party whose data reaches a log message could hide the rest of that record. Only applications on Windows that use EventLogAppender are affected.

This issue affects Apache log4net: from 1.2.9 before 3.5.0.

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

Affected Software

VendorProductVersion RangeStatus
Apache Software FoundationApache log4net1.2.9 < 3.5.0affected
Apache Software FoundationApache log4net02e1e115435888485f2e28b414d267e39e799e07 < dc5855a0720c91590fd7a81d729ea01fdd69e000affected

Weaknesses

  • CWE-158: CWE-158 Improper Neutralization of Null Byte or NUL Character

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: yes
    • Technical Impact: partial

References