CVE-2026-105242CWE-755

CVE-2026-105242

Medium · published October 7, 2026

CVSS v3.1
5.3
EPSS
1%
Percentile
56.9
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00823 · 56.9th percentile
Weakness
CWE-755 · Improper Handling of Exceptional Conditions
Published
2026-10-07T00:17Z
Affected products (1)
ProductVersionsFixed in
apache/log4net≥ 1.2.11, < 3.5.03.5.0
References (4)
https://github.com/apache/logging-log4net/commit/145203420c579a703008b4b723b6a080757f4964 · [email protected]https://github.com/apache/logging-log4net/pull/316 · [email protected]https://lists.apache.org/thread.html/zg6dbqm4ztm7j3c21nfsqj0yxm5yrpdx · [email protected]http://www.openwall.com/lists/oss-security/2026/10/07/16 · af854a3a-2127-422b-91ae-364da2661108
EPSS history
Timeline
  • 08 OCT 03:27Z
    EPSS moved — → 0%
    epss
  • 06 OCT 19:50Z
    Apache log4net: Request validation failure drops the event in the aspnet-request converter
    cvelistv5