The default MAC algorithm used in a PKCS #12 keystore has been updated. The new algorithm is based on SHA-256 and is stronger than the old one based on SHA-1. See the security properties starting with keystore.pkcs12 in the java.security file for detailed information.

The new SHA-256 based MAC algorithms were introduced in the 11.0.12, 8u301, and 7u311 JDK versions. Keystores created using this newer, stronger, MAC algorithm cannot be opened in JDK versions earlier than 11.0.12, 8u301, and 7u311. A 'java.security.NoSuchAlgorithmException' exception will be thrown in such circumstances.

For compatibility, use the keystore.pkcs12.legacy system property, which will revert the algorithms to use the older, weaker algorithms. There is no value defined for this property.

It is now possible to monitor deserialization of objects using JDK Flight Recorder (JFR). When JFR is enabled and the JFR configuration includes deserialization events, JFR will emit an event whenever the running program attempts to deserialize an object. The deserialization event is named jdk.Deserialization, and it is disabled by default. The deserialization event contains information that is used by the serialization filter mechanism; see the ObjectInputFilter specification. Additionally, if a filter is enabled, the JFR event indicates whether the filter accepted or rejected deserialization of the object. For further information about how to use the JFR deserialization event, see the article Monitoring Deserialization to Improve Application Security. For reference information about using and configuring JFR, see the JFR Runtime Guide and JFR Command Reference sections of the JDK Mission Control documentation.

JARs signed with SHA-1 algorithms are now restricted by default and treated as if they were unsigned. This applies to the algorithms used to digest, sign, and optionally timestamp the JAR. It also applies to the signature and digest algorithms of the certificates in the certificate chain of the code signer and the Timestamp Authority, and any CRLs or OCSP responses that are used to verify if those certificates have been revoked. These restrictions also apply to signed JCE providers.

To reduce the compatibility risk for JARs that have been previously timestamped, there is one exception to this policy:

• Any JAR signed with SHA-1 algorithms and timestamped prior to January 01, 2019 will not be restricted.

This exception may be removed in a future JDK release. To determine if your signed JARs are affected by this change, run jarsigner -verify -verbose -certs on the signed JAR, and look for instances of "SHA1" or "SHA-1" and "disabled" and a warning that the JAR will be treated as unsigned in the output.

For example:

-  Signed by "CN="Signer""

     Digest algorithm: SHA-1 (disabled)
     Signature algorithm: SHA1withRSA (disabled), 2048-bit key

WARNING: The jar will be treated as unsigned, because it is signed with a weak algorithm that is now disabled by the security property:

  jdk.jar.disabledAlgorithms=MD2, MD5, RSA keySize < 1024, DSA keySize < 1024, SHA1 denyAfter 2019-01-01

JARs affected by these new restrictions should be replaced or re-signed with stronger algorithms.

Users can, at their own risk, remove these restrictions by modifying the java.security configuration file (or override it by using the java.security.properties system property) and removing "SHA1 usage SignedJAR & denyAfter 2019-01-01" from the jdk.certpath.disabledAlgorithms security property and "SHA1 denyAfter 2019-01-01" from the jdk.jar.disabledAlgorithms security property.

The des3-hmac-sha1 and rc4-hmac Kerberos encryption types (etypes) are now deprecated and disabled by default. Users can set allow_weak_crypto = true in the krb5.conf configuration file to re-enable them (along with other weak etypes including des-cbc-crc and des-cbc-md5) at their own risk. To disable a subset of the weak etypes, users can list preferred etypes explicitly in any of the default_tkt_enctypes, default_tgs_enctypes, or permitted_enctypes settings.

Two system properties have been added which control the keep alive behavior of HttpURLConnection in the case where the server does not specify a keep alive time. Two properties are defined for controlling connections to servers and proxies separately. They are http.keepAlive.time.server and http.keepAlive.time.proxy respectively. More information about them can be found in Networking Properties.

Previous JDK releases used an incorrect interpretation of the Linux cgroups parameter "cpu.shares". This might cause the JVM to use fewer CPUs than available, leading to an under utilization of CPU resources when the JVM is used inside a container.

Starting from this JDK release, by default, the JVM no longer considers "cpu.shares" when deciding the number of threads to be used by the various thread pools. The -XX:+UseContainerCpuShares command-line option can be used to revert to the previous behavior. This option is deprecated and may be removed in a future JDK release.

This version includes changes from 2022b that merged multiple regions that have the same timestamp data post-1970 into a single time zone data. All time zone IDs remain the same but the merged time zones will point to a shared zone data.

As a result, pre-1970 data may not be compatible with earlier JDK versions. The affected zones are Antarctica/Vostok, Asia/Brunei, Asia/Kuala_Lumpur, Atlantic/Reykjavik, Europe/Amsterdam, Europe/Copenhagen, Europe/Luxembourg, Europe/Monaco, Europe/Oslo, Europe/Stockholm, Indian/Christmas, Indian/Cocos, Indian/Kerguelen, Indian/Mahe, Indian/Reunion, Pacific/Chuuk, Pacific/Funafuti, Pacific/Majuro, Pacific/Pohnpei, Pacific/Wake, Pacific/Wallis, Arctic/Longyearbyen, Atlantic/Jan_Mayen, Iceland, Pacific/Ponape, Pacific/Truk, and Pacific/Yap.

For more details, refer to the announcement of 2022b.

A new system property named jdk.httpserver.maxConnections has been introduced to allow users to configure the com.sun.net.httpserver.HttpServer to limit the maximum number of open connections to the server at any given time. This system property takes an integer value and can be configured to be a positive integer. If the property is absent, set to 0, or a negative value, the server will not limit the number of open connections. By default, this system property is not set.