JDK throws ArrayIndexOutOfBoundsException while parsing non RFC conforming CRL with revocation reason not in the range of accepted values. Checked with keytool and CertPathValidator.

with keytool:
    CRL Entry Extensions: 1
    [1]: , Error parsing this extension

Exception trace:

java.lang.ArrayIndexOutOfBoundsException: -1
        at sun.security.x509.CRLReasonCodeExtension.toString(CRLReasonCodeExtension.java:184)
        at java.lang.String.valueOf(String.java:2979)
        at java.lang.StringBuilder.append(StringBuilder.java:131)
        at java.util.AbstractMap.toString(AbstractMap.java:536)
        at java.lang.String.valueOf(String.java:2979)
        at java.lang.StringBuilder.append(StringBuilder.java:131)
        at java.security.cert.CertificateRevokedException.getMessage(CertificateRevokedException.java:173)
        at sun.security.provider.certpath.RevocationChecker.checkApprovedCRLs(RevocationChecker.java:655)
        at sun.security.provider.certpath.RevocationChecker.checkCRLs(RevocationChecker.java:567)