modules/arch/win32/modisapi.c in modisapi in the Apache HTTP Server 2.0.37 through 2.0.63, 2.2.0 through 2.2.14, and 2.3.x before 2.3.7, when running on Windows, does not ensure that request processing is complete before calling isapiunload for an ISAPI .dll module, which allows remote attackers to execute arbitrary code via unspecified vectors related to a crafted request, a reset packet, and "orphaned callback pointers."

The modssl module in Apache 2.0.35 through 2.0.52, when using the "SSLCipherSuite" directive in directory or location context, allows remote clients to bypass intended restrictions by using any cipher suite that is allowed by the virtual host configuration.

Unknown vulnerability in Apache 2.0.51 prevents "the merging of the Satisfy directive," which could allow attackers to obtain access to restricted resources contrary to the specified authentication configuration.

Martin Joey Schulze discovered a flaw in the way modauthmysql handles certain multibyte character encodings.

If modauthmysql is configured to use use a multibyte character set that allows the backslash '\' character as part of the character encodings, it is possible to inject arbitrary SQL commands to the MySQL database server.

An Uncontrolled Resource Consumption vulnerability in multiple products may allow an attacker to cause web service portal denial of service (DoS) via handling special crafted HTTP requests/responses in pieces slowly. Slow HTTP attacks are denial-of-service (DoS) attacks in which the attacker sends HTTP requests in pieces slowly, one at a time to a Web server. If an HTTP request is not complete, or if the transfer rate is very low, the server keeps its resources busy waiting for the rest of the data. When the server’s concurrent connection pool reaches its maximum, this creates a DoS. Slow HTTP attacks are easy to execute because they require only minimal resources from the attacker.

Format string vulnerability in the modtcl module 1.0 for Apache 2.x allows context-dependent attackers to execute arbitrary code via format string specifiers that are not properly handled in a setvar function call in (1) tclcmds.c and (2) tclcore.c.

Cross-site scripting (XSS) vulnerability in modautoindex.c in the Apache HTTP Server before 2.2.6, when the charset on a server-generated page is not defined, allows remote attackers to inject arbitrary web script or HTML via the P parameter using the UTF-7 charset. NOTE: it could be argued that this issue is due to a design limitation of browsers that attempt to perform automatic content type detection.

modssl in Apache 2.0 up to 2.0.55, when configured with an SSL vhost with access control and a custom error 400 error page, allows remote attackers to cause a denial of service (application crash) via a non-SSL request to an SSL port, which triggers a NULL pointer dereference.

The byte-range filter in Apache 2.0 before 2.0.54 allows remote attackers to cause a denial of service (memory consumption) via an HTTP header with a large Range field.

RMDG partner and independent security consultancy, "Context Information Security" has made CPNI Response aware of a security vulnerability which could potentially allow an attacker to gain full internal access to a network from the internet.

The technique exploits insecurely configured reverse web proxies to gain access to internal/DMZ systems.

This attack is based on an Apache web server which is using "modrewrite" to proxy web requests internally. Other proxies may suffer from this issue.

The vulnerability occurs if the Apache configuration file is configured like this:

RewriteRule ^(.) http://internalserver:80$1 [P]

As opposed to:

RewriteRule ^(.) http://internalserver:80/$1 [P]

It is important for readers to review their reverse proxy configurations to ensure that the rewrite rules are securely configured and cannot be abused in such a way that they can be used to compromise internal systems.

Integer overflow in the appregsub function in server/util.c in the Apache HTTP Server 2.0.x through 2.0.64 and 2.2.x through 2.2.21, when the modsetenvif module is enabled, allows local users to gain privileges via a .htaccess file with a crafted SetEnvIf directive, in conjunction with a crafted HTTP request header, leading to a heap-based buffer overflow.

Cross-site scripting (XSS) vulnerability in the modimap module of Apache httpd before 1.3.35-dev and Apache httpd 2.0.x before 2.0.56-dev allows remote attackers to inject arbitrary web script or HTML via the Referer when using image maps.

SUSE reported that upstream patch for CVE-2011-3368 (bug #740045), when applied to httpd versions before 2.2.18, does not completely address the issue, when attacker sends HTTP 0.9 requests::

https://bugzilla.novell.com/showbug.cgi?id=722545#c15 http://thread.gmane.org/gmane.comp.apache.devel/45978 http://thread.gmane.org/gmane.comp.security.oss.general/6102

The fix has been created upstream and committed to trunk:

http://thread.gmane.org/gmane.comp.apache.devel/45978/focus=45979 http://svn.apache.org/viewvc?view=revision&revision=1188745

Upstream also confirmed this additional fix is not required for httpd versions 2.2.18 and later:

http://thread.gmane.org/gmane.comp.apache.devel/45978/focus=45983 http://thread.gmane.org/gmane.comp.apache.devel/45978/focus=45985

Additional problems were discovered in the httpd fix for CVE-2011-3368 - a reverse proxy bypass flaw - tracked via bug #740045. Upstream mailing list post identifies following request forms, which are not handled correctly:

GET @localhost::8880 HTTP/1.0\r\n\r\n GET qualys:@qqq.qq.qualys.com HTTP/1.0\r\n\r\n

Reference: http://thread.gmane.org/gmane.comp.apache.devel/46440

Cross-site scripting (XSS) vulnerability in Apache 2.2.6 and earlier allows remote attackers to inject arbitrary web script or HTML via UTF-7 encoded URLs that are not properly handled when displaying the 403 Forbidden error page.

Cross-site scripting (XSS) vulnerability in modstatus in the Apache HTTP Server 2.2.0 through 2.2.6, 2.0.35 through 2.0.61, and 1.3.2 through 1.3.39, when the server-status page is enabled, allows remote attackers to inject arbitrary web script or HTML via unspecified vectors.

Apache HTTP Server 2.0.x and 2.2.x does not sanitize the HTTP Method specifier header from an HTTP request when it is reflected back in a "413 Request Entity Too Large" error message, which might allow cross-site scripting (XSS) style attacks using web client components that can send arbitrary headers in requests, as demonstrated via an HTTP request containing an invalid Content-length value, a similar issue to CVE-2006-3918.

It was reported [1] that an integer overflow was found in Apache in the appregsub() function called from mod-setenvif. When a header field is mangled using SetEnvIf, the new environment variable data can be multiples of the size of the submitted header field. This would cause appregsub() to overflow the length value in buffer size calculations, leading to the subsequent allocation call of a too-small buffer. Filling this buffer with user-supplied data will lead to a buffer overflow.

Depending on the input data, this can lead to excessive allocation of server memory (resulting in killed processes due to out-of-memory conditions), invalid memory access when copying large amounts of data (which can lead to a termination of the httpd process), or possibly allowing the execution of arbitrary code.

To trigger this flaw, modsetenvif must be enabled (the default) and the attacker needs to be able to place a crafted .htaccess file on the server (which, in most cases, would require local access to the file system or some web interface that allows for writing arbitrary files to the local file system, such as for custom .htaccess files).

There is currently no upstream fix, however to work around the problem, disable modsetenvif.

[1] http://www.halfdog.net/Security/2011/ApacheModSetEnvIfIntegerOverflow/