Opera before 9.0 does not reset the SSL security bar after displaying a download dialog from an SSL-enabled website, which allows remote attackers to spoof a trusted SSL certificate from an untrusted website and facilitates phishing attacks.
Integer signedness error in Opera before 8.54 allows remote attackers to execute arbitrary code via long values in a stylesheet attribute, which pass a length check. NOTE: a sign extension problem makes the attack easier with shorter strings.