Apache LOG4NET vulnerabilities

9 CVEs affecting Apache LOG4NET, 0 known to be exploited (CISA KEV), with EPSS scores. Latest: CVE-2026-105244, published 2026-10-06.

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Known exploited (CISA KEV) first, then by EPSS exploit probability.

• CVE-2018-1285, published 2020-05-11. Critical severity, CVSS 9.8. EPSS: 17.8% chance of exploitation in the next 30 days. Apache log4net versions before 2.0.10 do not disable XML external entities when parsing log4net configuration files. This allows for XXE-based attacks in applications that accept attacker-controlled…
• CVE-2006-0743, published 2006-03-09. Medium severity, CVSS 5.0. EPSS: 6.4% chance of exploitation in the next 30 days. Format string vulnerability in LocalSyslogAppender in Apache log4net 1.2.9 might allow remote attackers to cause a denial of service (memory corruption and termination) via unknown vectors.
• CVE-2026-40021, published 2026-04-10. Medium severity, CVSS 5.3. EPSS: 1% chance of exploitation in the next 30 days. Apache Log4net's XmlLayout https://logging.apache.org/log4net/manual/configuration/layouts.html#layout-list and XmlLayoutSchemaLog4J…
• CVE-2026-105244, published 2026-10-06. Medium severity, CVSS 5.3. EPSS: 0.8% chance of exploitation in the next 30 days. Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net. Every character outside visible ASCII and space was removed from the record instead of being…
• CVE-2026-105242, published 2026-10-06. Medium severity, CVSS 5.3. EPSS: 0.8% chance of exploitation in the next 30 days. 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…
• CVE-2026-105241, published 2026-10-06. Medium severity, CVSS 5.3. EPSS: 0.8% chance of exploitation in the next 30 days. Improper Handling of Unicode Encoding vulnerability in the SmtpPickupDirAppender of Apache log4net. Content that the mail file writer cannot encode, such as an unpaired UTF-16 surrogate, made the…
• CVE-2026-105239, published 2026-10-06. Medium severity, CVSS 5.3. EPSS: 0.8% chance of exploitation in the next 30 days. Improper Neutralization of Null Byte or NUL Character vulnerability in the EventLogAppender of Apache log4net. A NUL character in logged content ended the Windows Event Log record at that point, so…
• CVE-2026-105243, published 2026-10-06. Medium severity, CVSS 5.3. EPSS: 0.8% chance of exploitation in the next 30 days. Insufficient Logging vulnerability in the EventLogAppender of Apache log4net. Long messages were truncated to a fixed size that exceeds what the Windows Event Log accepts once the log and source…
• CVE-2026-105240, published 2026-10-06. Medium severity, CVSS 5.3. EPSS: 0.8% chance of exploitation in the next 30 days. Improper Neutralization of Null Byte or NUL Character vulnerability in the OutputDebugStringAppender of Apache log4net. A NUL character in logged content ended the debug output record at that point,…