Oracle recommends that the JDK is updated with each Critical Patch Update. In order to determine if a release is the latest, the Security Baseline page can be used to determine which is the latest version for each release family.

Critical patch updates, which contain security vulnerability fixes, are announced one year in advance on Critical Patch Updates, Security Alerts and Bulletins. It is not recommended that this JDK (version 17.0.5) be used after the next critical patch update scheduled for January 17, 2023.

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signer and the Timestamp Authority, and any CRLs or OCSP responses that are used to verify if those certificates have been revoked.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.

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.

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.