Apache HTTP Server 2.0.47 and earlier allows local users to bypass .htaccess file restrictions, as specified in httpd.conf with directives such as Deny From All, by using an ErrorDocument directive. NOTE: the vendor has disputed this issue, since the .htaccess mechanism is only intended to restrict external web access, and a local user already has the privileges to perform the same operations without using ErrorDocument

PHP 4.3.4 and earlier in Apache 1.x and 2.x (mod_php) can leak global variables between virtual hosts that are handled by the same Apache child process but have different settings, which could allow remote attackers to obtain sensitive information.

Heap-based buffer overflow in proxy_util.c for mod_proxy in Apache 1.3.25 to 1.3.31 allows remote attackers to cause a denial of service (process crash) and possibly execute arbitrary code via a negative Content-Length HTTP header field, which causes a large amount of data to be copied.

Apache 1.4.x before 1.3.30, and 2.0.x before 2.0.49, when using multiple listening sockets on certain platforms, allows remote attackers to cause a denial of service (blocked new connections) via a "short-lived connection on a rarely-accessed listening socket."

mod_access in Apache 1.3 before 1.3.30, when running big-endian 64-bit platforms, does not properly parse Allow/Deny rules using IP addresses without a netmask, which could allow remote attackers to bypass intended access restrictions.

mod_digest for Apache before 1.3.31 does not properly verify the nonce of a client response by using a AuthNonce secret.

mod_digest_apple for Apache 1.3.31 and 1.3.32 on Mac OS X Server does not properly verify the nonce of a client response, which allows remote attackers to replay credentials.

Apache does not filter terminal escape sequences from its error logs, which could make it easier for attackers to insert those sequences into terminal emulators containing vulnerabilities related to escape sequences.

The log files in Apache web server contain information directly supplied by clients and does not filter or quote control characters, which could allow remote attackers to hide HTTP requests and spoof source IP addresses when logs are viewed with UNIX programs such as cat, tail, and grep.