CVE-2026-105242

Name	CVE-2026-105242
Description	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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
log4net (PTS)	trixie	1.2.10+dfsg-9	fixed
	forky, sid	1.2.10+dfsg-10	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
log4net	source	(unstable)	(not affected)

Notes

- log4net <not-affected> (Vulnerable code introduced later)
https://github.com/apache/logging-log4net/pull/316
Fixed by: https://github.com/apache/logging-log4net/commit/145203420c579a703008b4b723b6a080757f4964 (rc/3.5.0-rc1)
https://lists.apache.org/thread/zg6dbqm4ztm7j3c21nfsqj0yxm5yrpdx