Medium 5.3Published Oct 6, 2026

CVE-2026-105242Apache log4net: Request validation failure drops the event in the aspnet-request converter

Updated under an hour ago (2026-10-19 07:30 UTC)

Does this affect you?

It affects Apache Software Foundation Apache log4net and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for Apache Software Foundation Apache log4net

Exploited in the last 30 days

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.

CVSS: 5.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Weakness (CWE): CWE-755
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: apache
NVD analysis: Analyzed
Record last updated: Oct 7, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Apache Software Foundation Apache log4net apache_software_foundation:apache_log4net (from the name)	from 1.2.11 before 3.5.0	CNA record
apache log4net apache:log4net	from 1.2.11 before 3.5.0	NVD

References

https://github.com/apache/logging-log4net/pull/316patch
https://github.com/apache/logging-log4net/commit/145203420c579a703008b4b723b6a080757f4964patch
https://lists.apache.org/thread.html/zg6dbqm4ztm7j3c21nfsqj0yxm5yrpdxvendor-advisory, mailing-list
http://www.openwall.com/lists/oss-security/2026/10/07/16mailing-list, third-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.