The dbm and shm session cache code in mod_ssl before 2.8.7-1.3.23, and Apache-SSL before 1.3.22+1.46, does not properly initialize memory using the i2d_SSL_SESSION function, which allows remote attackers to use a buffer overflow to execute arbitrary code via a large client certificate that is signed by a trusted Certificate Authority (CA), which produces a large serialized session.

Apache-SSL 1.3.28+1.52 and earlier, with SSLVerifyClient set to 1 or 3 and SSLFakeBasicAuth enabled, allows remote attackers to forge a client certificate by using basic authentication with the "one-line DN" of the target user.