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TI-2026-68922 Aliases CVE-2026-105242GHSA-r886-mf8r-26c7

Log4net drops log events when ASP.NET request validation fails

Priority LOW 32CWE-755Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · Low · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

Apache log4net from 1.2.11 before 3.5.0 has an improper handling of exceptional conditions flaw in its aspnet-request pattern converter (CWE-755). Reading request parameters triggers ASP.NET request validation, so a request containing markup makes the layout throw and the appender discards the whole log event. A remote sender can suppress the log record of their own request. Only ASP.NET for .NET Framework applications whose layout uses %aspnet-request are affected.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00823 57th percentileScored 2026-11-07
Fix Fixed Apache log4net (Apache Software Foundation): 3.5.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ApacheApache log4net1.2.11 to before 3.5.03.5.0Patch availableCNA
  • Apache log4net VendorApache Affected 1.2.11 to before 3.5.0 Fixed in 3.5.0 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:apache:log4net:*:*:*:*:*:*:*:*1.2.11 to before 3.5.0VulnerableApache
  • cpe:2.3:a:apache:log4net:*:*:*:*:*:*:*:* Versions 1.2.11 to before 3.5.0 Vulnerable ·Apache

Remediation

Upgrade Apache log4net to version 3.5.0, which fixes the issue. The sources list no fixed version for Red Hat products.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

  • Fix · CNA Apache log4net (Apache Software Foundation) Fixed in 3.5.0

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    Apache log4net 3.5.0

    6 records Highest priority Priority LOW 6 LOW

    Other records, highest priority first

    • TI-2026-68924 RemoteSyslogAppender in Apache log4net silently drops non-ASCII textPriority LOW 32
    • TI-2026-68923 Apache log4net EventLogAppender silently discards oversize recordsPriority LOW 32
    • TI-2026-68921 Unencodable content drops a whole batch in Apache log4net appenderPriority LOW 32
    Show all 6 records →

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-06 Threatist record created from CVE-2026-105242
  2. 2026-10-07 Alias added: GHSA-r886-mf8r-26c7
  3. 2026-10-07 CISA SSVC decision points changed
  4. 2026-10-07 Affected versions changed · Red Hat
  5. 2026-10-07 CVSS score added · Red Hat
  6. 2026-10-11 EPSS moved to the 50th–90th percentile

References

Patch 2

Advisory 2

  • TI-2018-01190 XML external entity injection in Apache log4net CVSS 3.1CRITICAL 9.8
  • TI-2026-68924 RemoteSyslogAppender in Apache log4net silently drops non-ASCII text CVSS 3.1MEDIUM 5.3
  • TI-2026-68923 Apache log4net EventLogAppender silently discards oversize records CVSS 3.1MEDIUM 5.3
  • TI-2026-68921 Unencodable content drops a whole batch in Apache log4net appender CVSS 3.1MEDIUM 5.3
  • TI-2026-68920 NUL character truncates log records in Apache log4net debug output CVSS 3.1MEDIUM 5.3
  • TI-2026-68919 NUL character truncates EventLogAppender records in Apache log4net CVSS 3.1MEDIUM 5.3
See all 8 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences