What is CVE-2026-105242?

CVE-2026-105242 is a medium-severity vulnerability in Apache Software Foundation Log4net, classified under Improper Handling of Exceptional Conditions. CVSS score: 5.3/10. Published 2026-10-06.

How severe is CVE-2026-105242?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Apache Software Foundation Log4net

CVE-2026-105242

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.

Published 2026-10-06 · last modified 2026-10-07.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Apache Software Foundation Log4net

Weakness classification (CWE)

CWE-755 — Improper Handling of Exceptional Conditions

References

Frequently asked questions

What is CVE-2026-105242?: CVE-2026-105242 is a medium-severity vulnerability in Apache Software Foundation Log4net, classified under Improper Handling of Exceptional Conditions. CVSS score: 5.3/10. Published 2026-10-06.
How severe is CVE-2026-105242?: Medium severity. CVSS v3 base score is 5.3 out of 10.