Nexus Repository Manager versions earlier than 2.14.5 MAY be affected. See below for exact details.
National Vulnerability Database
Sonatype CVSS 3.0: 9.8
Sonatype CWE: 502
Description from CVE
The RemoteStreamAppenderClient class in logback-classic and the SocketNode classes in logback-classic and logback-access allow data to be deserialized over a Java Socket, via an ObjectInputStream, without validating the data beforehand. When data is received from the Socket, to be logged, it is deserialized into Java objects. An attacker can exploit this vulnerability by sending malicious, serialized Java objects over the connection to the Socket, which may result in execution of arbitrary code when those objects are deserialized.
Note that although logback-core is implicated by the Logback project here, the Sonatype Security Research team discovered that the vulnerability is actually present in the logback-classic and logback-access components.
Advisory Deviation Notice: The Sonatype Security Research team discovered that this vulnerability was first introduced in version 0.3.0 of logback-classic and version 0.6.0 of logback-access, as opposed to being present in all versions prior to 1.2.0, as stated in the advisory.
The application is vulnerable by using this component.
We recommend upgrading to a version of this component that is not vulnerable to this specific issue.
logback-classic-1.1.2.jar <= SocketNode.class : [1.0.12,1.2.0)
logback-classic-1.1.2.jar <= RemoteAppenderStreamClient.class : [1.0.12,1.2.0)
Nexus 3.x: Because NX3 ships with a modified and repackaged logback bundle (derived from the pax-logging project) it doesn't appear to be affected.
Nexus 2.x: Regarding the actual CVE, the out-of-the-box logback configuration we ship with is not vulnerable. The issue may be applicable if an installation of Nexus added a "receiver" to the logback configuration: https://logback.qos.ch/manual/receivers.html , however doing so would be outside the scope of something Sonatype would advise doing and we have no known installations with such a configuration.
Nexus Repository Manager 2.14.5 ships with a version of logback not vulnerable.