Use of Externally-Controlled Format String
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.
Advisories for Nuget/Log4net package
2022
2020
Improper Restriction of XML External Entity Reference
Apache log4net do not disable XML external entities when parsing log4net configuration files. This allows for XXE-based attacks in applications that accept attacker-controlled log4net configuration files.