includes/User.php in MediaWiki before 1.19.12, 1.20.x and 1.21.x before 1.21.6, and 1.22.x before 1.22.3 terminates validation of a user token upon encountering the first incorrect character, which makes it easier for remote attackers to obtain access via a brute-force attack that relies on timing differences in responses to incorrect token guesses.

References

• https://nvd.nist.gov/vuln/detail/CVE-2014-2243
• https://bugzilla.redhat.com/show_bug.cgi?id=1071136
• https://bugzilla.wikimedia.org/show_bug.cgi?id=61346
• https://gerrit.wikimedia.org/r/#/q/I2a9e89120f7092015495e638c6fa9f67adc9b84f,n,z
• http://lists.wikimedia.org/pipermail/mediawiki-announce/2014-February/000141.html
• http://openwall.com/lists/oss-security/2014/02/28/1
• http://openwall.com/lists/oss-security/2014/03/01/2