It was discovered that OpenJDK did not properly validate types in some situations.
It was discovered that the PatternSyntaxException class in OpenJDK did not properly validate arguments passed to it.
It was discovered a vulnerability in the Galois/Counter Mode (GCM) mode of operation for symmetric block ciphers in OpenJDK.
An attacker could use this to construct a Java class that could possibly bypass sandbox restrictions. (CVE-2018-2825, CVE-2018-2826)
An attacker could use this to potentially construct a class that caused a denial of service (excessive memory consumption). (CVE-2018-2952)
An attacker could use this to expose sensitive information. (CVE-2018-2972)
Refer to Ubuntu advisory USN-3747-1 for affected packages and patching details, or update with your package manager.
Following are links for downloading patches to fix the vulnerabilities: