The HTTPS protocol, as used in unspecified web applications, can encrypt compressed data without properly obfuscating the length of the unencrypted data, which makes it easier for man-in-the-middle attackers to obtain plaintext secret values by observing length differences during a series of guesses in which a string in an HTTP request URL potentially matches an unknown string in an HTTP response body, aka a "BREACH" attack, a different issue than CVE-2012-4929.