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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-105242
StatePUBLISHED
Assignerapache
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-06 20:17:16 UTC
Updated2026-10-06 20:17:16 UTC
DescriptionImproper 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.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Problem Types: CWE-755 | CWE-755 CWE-755 Improper Handling of Exceptional Conditions

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
3.1CNACVSS5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Apache Software Foundation Apache Log4net affected 1.2.11 3.5.0 semver Not specified
CNA Apache Software Foundation Apache Log4net affected 243f1e9f3ee235955bade4b4fe664a903378719a 145203420c579a703008b4b723b6a080757f4964 git Not specified

References

ReferenceSourceLinkTags
github.com/apache/logging-log4net/pull/316 [email protected] github.com
lists.apache.org/thread.html/zg6dbqm4ztm7j3c21nfsqj0yxm5yrpdx [email protected] lists.apache.org
github.com/apache/logging-log4net/commit/145203420c579a703008b4b723b6a08... [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: The Apache Software Foundation (en)

CNA: Claude Security (en)

CNA: Jan Friedrich (en)

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report