This issue is listed as fixed through 1.48 changelog, though still unresolved, is this true?
Gonna check the commits.

At least https://github.com/jenkinsci/active-directory-plugin/commit/d8495d702d4e526d76d3b700744db86bb0a84eb3

Released in 1.48

For reference, now with that change:

 /**
     * Timeout if no connection after 30 seconds
    */
    private final static String DEFAULT_LDAP_CONNECTION_TIMEOUT = "30000";
    /**
     * Timeout if no response after 60 seconds
     */
    private final static String DEFAULT_LDAP_READ_TIMEOUT = "60000";

Issue is not yet fixed.

The connection timeout can not be used due to an Oracle JDK bug.

teilo seems like we need some context or reference for your comment.

It's all in the PR.
Direct link https://github.com/jenkinsci/active-directory-plugin/pull/37/commits/a037bde7e17fdfc9286644cd7a905f7b8e398ed2

Not use for the moment DEFAULT_LDAP_CONNECTION_TIMEOUT since JDK-8139721, JDK-8139942 breaks the plugin usage

[https://bugs.openjdk.java.net/browse/JDK-8139721 | JDK-8139721]

However the workaround seems not to work...

The issue seems to be
https://github.com/jenkinsci/active-directory-plugin/blob/active-directory-2.0/src/main/java/hudson/plugins/active_directory/ActiveDirectorySecurityRealm.java#L572 specifically because the property should not be added if the connection is not running through SSL. Once you correctly handle this, DEFAULT_LDAP_CONNECTION_TIMEOUT seems to work. I am working on a fix.

newProps.put("java.naming.ldap.factory.socket",TrustAllSocketFactory.class.getName());

Code changed in jenkins
User: Félix Belzunce Arcos
Path:
src/main/java/hudson/plugins/active_directory/ActiveDirectorySecurityRealm.java
src/main/java/hudson/plugins/active_directory/ActiveDirectoryUnixAuthenticationProvider.java
http://jenkins-ci.org/commit/active-directory-plugin/7b68679b4425ae12700ed2b0dd3ec0df16f91343
Log:
JENKINS-36041 Enable com.sun.jndi.ldap.connect.timeout

Code changed in jenkins
User: Felix Belzunce Arcos
Path:
src/main/java/hudson/plugins/active_directory/ActiveDirectorySecurityRealm.java
src/main/java/hudson/plugins/active_directory/ActiveDirectoryUnixAuthenticationProvider.java
http://jenkins-ci.org/commit/active-directory-plugin/f80f9555dbe17d61bd4e310e996cd95ee90fad1a
Log:
Merge pull request #62 from fbelzunc/JENKINS-36041-v4

[FIXED JENKINS-36041 JENKINS-25269] Enable com.sun.jndi.ldap.connect.timeout

Compare: https://github.com/jenkinsci/active-directory-plugin/compare/95effde74165...f80f9555dbe1

Will be released in version 2.1