wp-admin/admin.php in WordPress and WordPress MU before 2.8.1 does not require administrative authentication to access the configuration of a plugin, which allows remote attackers to specify a configuration file in the page parameter to obtain sensitive information or modify this file, as demonstrated by the (1) collapsing-archives/options.txt, (2) akismet/readme.txt, (3) related-ways-to-take-action/options.php, (4) wp-security-scan/securityscan.php, and (5) wp-ids/ids-admin.php files. NOTE: this can be leveraged for cross-site scripting (XSS) and denial of service.
CWE-287 - Improper Authentication
Improper (or broken) authentication attacks are widespread, and have accounted for many of the worst data breaches in recent years. Improper authentication attacks are a class of vulnerabilities where an attacker impersonates a legitimate user by exploiting weaknesses in either session management or credential management to gain access to the user’s account. This can result in disclosure of sensitive information, and can lead to system compromise, theft, identity theft, and fraud.