Apple has pushed out a massive patch to address nearly 60 vulnerabilities affecting Mac OS X.

The most serious of the flaws can be exploited by a remote attacker to take over a vulnerable system. Most of the vulnerabilities impact Snow Leopard, the latest version of Apple’s operating system. The batch of fixes addresses more than three times as many vulnerabilities as the update in August, which fixed 18 issues.

Among the most serious of the bugs is a memory corruption issue in DirectoryService that may allow a remote attacker to trigger an application crash or execute arbitrary code. According to Apple, the issue only affects systems configured as DirectoryService servers.

Apple’s CoreGraphics component has multiple integer overflows tied to its handling of PDF files that can result in a heap buffer overflow. Opening a malicious PDF file can lead to application termination or arbitrary code execution, Apple warned, and the patch fixes the situation by improving bounds checking.

Also fixed is an issue involving Apple’s Adaptive Firewall. In certain circumstances, the firewall may not detect SSH login attempts using invalid user names, Apple states in an advisory. The patch resolves the issue by improving detection of invalid SSH login attempts.

Apple also removed support for X.509 certificates with MD2 hashes for any use other than as trusted root certificates, stating that they may expose users to spoofing and "information disclosure as attacks improve.”

“There are known cryptographic weaknesses in the MD2 hash algorithm,” the advisory states. “Further research could allow the creation of X.509 certificates with attacker controlled values that are trusted by the system. This could expose X.509 based protocols to spoofing, man in the middle attacks, and information disclosure.”

Several of the fixes address security issues in QuickTime and open-source components such as Apache, OpenLDAP and OpenSSH. According to Apple, there's an implementation issue in OpenLDAP’s handling of SSL certificates that have NUL characters in the Common Name field.

“Using a maliciously crafted SSL certificate, an attacker may be able to perform a man-in-the-middle attack on OpenLDAP transactions which use SSL," according to Apple. “This update addresses the issue through improved handling of SSL certificates.”