Weak named curves are disabled by default by adding them to the following disabledAlgorithms security properties: jdk.tls.disabledAlgorithms, jdk.certpath.disabledAlgorithms, and jdk.jar.disabledAlgorithms. The named curves are listed below.

With 47 weak named curves to be disabled, adding individual named curves to each disabledAlgorithms property would be overwhelming. To relieve this, a new security property, jdk.disabled.namedCurves, is implemented that can list the named curves common to all of the disabledAlgorithms properties. To use the new property in the disabledAlgorithms properties, precede the full property name with the keyword include. Users can still add individual named curves to disabledAlgorithms properties separate from this new property. No other properties can be included in the disabledAlgorithms properties.

To restore the named curves, remove the include jdk.disabled.namedCurves either from specific or from all disabledAlgorithms security properties. To restore one or more curves, remove the specific named curve(s) from the jdk.disabled.namedCurves property.

Curves that are disabled through jdk.disabled.namedCurves include the following: secp112r1, secp112r2, secp128r1, secp128r2, secp160k1, secp160r1, secp160r2, secp192k1, secp192r1, secp224k1, secp224r1, secp256k1, sect113r1, sect113r2, sect131r1, sect131r2, sect163k1, sect163r1, sect163r2, sect193r1, sect193r2, sect233k1, sect233r1, sect239k1, sect283k1, sect283r1, sect409k1, sect409r1, sect571k1, sect571r1, X9.62 c2tnb191v1, X9.62 c2tnb191v2, X9.62 c2tnb191v3, X9.62 c2tnb239v1, X9.62 c2tnb239v2, X9.62 c2tnb239v3, X9.62 c2tnb359v1, X9.62 c2tnb431r1, X9.62 prime192v2, X9.62 prime192v3, X9.62 prime239v1, X9.62 prime239v2, X9.62 prime239v3, brainpoolP256r1, brainpoolP320r1, brainpoolP384r1, brainpoolP512r1

Curves that remain enabled are: secp256r1, secp384r1, secp521r1, X25519, X448

The Kerberos client has been enhanced with the support of principal name canonicalization and cross-realm referrals, as defined by the RFC 6806 protocol extension.

As a result of this new feature, the Kerberos client can take advantage of more dynamic environment configurations and does not necessarily need to know (in advance) how to reach the realm of a target principal (user or service).

Support is enabled by default and 5 is the maximum number of referral hops allowed. To turn it off, set the sun.security.krb5.disableReferrals security or system property to false. To configure a custom maximum number of referral hops, set the sun.security.krb5.maxReferrals security or system property to any positive value.

See further information in JDK-8223172.

A new system property, jdk.tls.maxHandshakeMessageSize, has been added to set the maximum allowed size for the handshake message in TLS/DTLS handshaking. The default value of the system property is 32768 (32 kilobytes).

A new system property, jdk.tls.maxCertificateChainLength, has been added to set the maximum allowed length of the certificate chain in TLS/DTLS handshaking. The default value of the system property is 10.

The keytool and jarsigner tools have been updated to warn users when weak cryptographic algorithms are used in keys, certificates, and signed JARs before they are disabled. The weak algorithms are set in the jdk.security.legacyAlgorithms security property in the java.security configuration file. In this release, the tools issue warnings for the SHA-1 hash algorithm and 1024-bit RSA/DSA keys.

The 'canonicalize' flag in the krb5.conf file is now supported by the JDK Kerberos implementation. When set to true, RFC 6806 name canonicalization is requested by clients in TGT requests to KDC services (AS protocol). Otherwise, and by default, it is not requested.

The new default behavior is different from JDK 14 and previous releases where name canonicalization was always requested by clients in TGT requests to KDC services (provided that support for RFC 6806 was not explicitly disabled with the sun.security.krb5.disableReferrals system or security properties).

NPAPI is considered to be a vulnerable plugin and has been disabled in many browsers. No browsers currently support Java Plugin, which is NPAPI-based, on Linux, Solaris, and MacOS platforms.

Starting from 8u271, the part of Java Plugin responsible for integration and interaction with a browser (in particular libnpjp2 library) and an associated artifact will not be built and is not part of the JRE distribution on Linux, Solaris, and MacOS platforms.

A new environment property, jdk.jndi.ldap.mechsAllowedToSendCredentials, has been added to control which LDAP authentication mechanisms are allowed to send credentials over clear LDAP connections - a connection not secured with TLS. An encrypted LDAP connection is a connection opened by using ldaps scheme, or a connection opened by using ldap scheme and then upgraded to TLS with a STARTTLS extended operation.

The value of the property, which is by default not set, is a comma separated list of the mechanism names that are permitted to authenticate over a clear connection. If a value is not specified for the property, then all mechanisms are allowed. If the specified value is an empty list, then no mechanisms are allowed (except for none and anonymous). The default value for this property is 'null' ( i.e. System.getProperty("jdk.jndi.ldap.mechsAllowedToSendCredentials") returns 'null'). To explicitly permit all mechanisms to authenticate over a clear connection, the property value can be set to "all". If a connection is downgraded from encrypted to clear, then only the mechanisms that are explicitly permitted are allowed.

The property can be supplied to the LDAP context environment map, or set globally as a system property. When both are supplied, the environment map takes precedence.

Note: none and anonymous authentication mechanisms are exempted from these rules and are always allowed regardless of the property value.

The following root certificates have been added to the cacerts truststore:

+ SSL Corporation

  + sslrootrsaca
    DN: CN=SSL.com Root Certification Authority RSA, O=SSL Corporation, L=Houston, ST=Texas, C=US

  + sslrootevrsaca
    DN: CN=SSL.com EV Root Certification Authority RSA R2, O=SSL Corporation, L=Houston, ST=Texas, C=US

  + sslrooteccca
    DN: CN=SSL.com Root Certification Authority ECC, O=SSL Corporation, L=Houston, ST=Texas, C=US

The following root certificate has been added to the cacerts truststore:

+ Entrust

  + entrustrootcag4
    DN: CN=Entrust Root Certification Authority - G4, OU="(c) 2015 Entrust, Inc. - for authorized use only", 
        OU=See www.entrust.net/legal-terms, O="Entrust, Inc.", C=US

Communication with the alternatives framework of JDK RPM installer starting from 8u261 has changed. JDK RPM installers of prior versions registered two groups of symbolic links with alternatives framework, java and javac. Some names of links in these groups were duplicated, which resulted in installation failures for some versions of alternatives framework. The JDK RPM installer beginning with 8u261 doesn't register the javac group with alternatives framework. All links unique to the javac group have been moved into the java group, but the set of symbolic links registered by the installer have not changed; only the duplicated links have been dropped.

The implication of this change is that if this version of JDK and 8u251 or older versions of the JDK are installed and the previous version is uninstalled, the symbolic links from the java group that are managed by the alternatives framework will be deleted. To restore deleted links, run the command:

/usr/sbin/alternatives --auto java

Some text in the Installer window is hidden/invisible when using Dark mode on macOS. To workaround this issue, switch to Light mode when running the installer. This issue should be resolved by JDK-8249683.

The deserialization of java.lang.reflect.Proxy objects can be limited by setting the system property jdk.serialProxyInterfaceLimit. The limit is the maximum number of interfaces allowed per Proxy in the stream. Setting the limit to zero prevents any Proxies from being deserialized including Annotations, a limit of less than 2 might interfere with RMI operations.