---
id: CVE-2026-105242
title: >-
  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 l…
summary: >-
  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 l…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'
cwe:
  - CWE-755
vendor: apache
product: log4net
affected:
  - 'log4net >= 1.2.11, < 3.5.0'
patched:
  - log4net 3.5.0
published: '2026-10-06'
updated: '2026-10-09'
sourceUpdated: '2026-10-09T15:28:34.500'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-105242'
references:
  - url: >-
      https://github.com/apache/logging-log4net/commit/145203420c579a703008b4b723b6a080757f4964
    label: security@apache.org
  - url: 'https://github.com/apache/logging-log4net/pull/316'
    label: security@apache.org
  - url: 'https://lists.apache.org/thread.html/zg6dbqm4ztm7j3c21nfsqj0yxm5yrpdx'
    label: security@apache.org
  - url: 'http://www.openwall.com/lists/oss-security/2026/10/07/16'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
  - cve.org
epss: 0.00823
epssPercentile: 0.57157
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-07T14:48:50.404406Z'
ingestedAt: '2026-10-06T20:16:42.477Z'
---

## Overview

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.

## Affected

- `log4net >= 1.2.11, < 3.5.0`

## Remediation

Upgrade past the affected range:

- `log4net 3.5.0`