CVE-2026-105242
Improper Handling of Exceptional Conditions vulnerability in the aspnet-request pattern converter of Apache log4net.
Does this matter?
Lower severity and a low EPSS score (0.82%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 3.1
- 5.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- EPSS
- 0.82% probability · 57th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-755
- Affected
- apache/log4net
- Source
- security@apache.org
EPSS moved from 0.3% on 7 October 2026 to 0.8% on 26 October 2026.
References
- https://github.com/apache/logging-log4net/commit/145203420c579a703008b4b723b6a080757f4964Patch
- https://github.com/apache/logging-log4net/pull/316Patch
- https://lists.apache.org/thread.html/zg6dbqm4ztm7j3c21nfsqj0yxm5yrpdxMailing List, Vendor Advisory
- http://www.openwall.com/lists/oss-security/2026/10/07/16Mailing List, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.