A flaw was found in the Apache Log4j logging library 2.x. when the logging configuration uses a non-default Pattern Layout with a Context Lookup. Attackers with control over Thread Context Map (MDC) input data can craft malicious input data that contains a recursive lookup and can cause Denial of Service.

sshd in OpenSSH before 6.6 does not properly support wildcards on AcceptEnv lines in sshdconfig, which allows remote attackers to bypass intended environment restrictions by using a substring located before a wildcard character.

apache. Multiple issues existed in Apache. These were addressed by updating Apache to version 2.4.25.

The following flaw was found in ntpd:

Using a crafted packet to create a peer association with hmode > 7 causes the MATCHASSOC() lookup to make an out-of-bounds reference.

Upstream bugs:

http://support.ntp.org/bin/view/Main/NtpBug3009

External References:

http://support.ntp.org/bin/view/Main/SecurityNotice#April2016NTP428p7Security

Heap-based buffer overflow in the nsshostnamedigitsdots function in glibc 2.2, and other 2.x versions before 2.18, allows context-dependent attackers to execute arbitrary code via vectors related to the (1) gethostbyname or (2) gethostbyname2 function, aka "GHOST."

Dominic Scheirlinck of VendHQ reports:

Many software projects and vendors have implemented support for the “Proxy” request header in their respective CGI implementations and languages by creating the “HTTPPROXY” environmental variable based on the header value. When this variable is used (in many cases automatically by various HTTP client libraries) any outgoing requests generated in turn from the attackers original request can be redirected to an attacker controlled proxy. This allows attackers to view potentially sensitive information, reply with malformed data, or to hold connections open causing a potential denial of service.

The PHP web framework contains will automatically populate the HTTPPROXY environmental variable with a user supplied "Proxy" header.