A flaw was found in the bash package, where a heap-buffer overflow can occur in valid parametertransform. This issue may lead to memory problems.
An issue was discovered in disableprivmode in shell.c in GNU Bash through 5.0 patch 11. By default, if Bash is run with its effective UID not equal to its real UID, it will drop privileges by setting its effective UID to its real UID. However, it does so incorrectly. On Linux and other systems that support "saved UID" functionality, the saved UID is not dropped. An attacker with command execution in the shell can use "enable -f" for runtime loading of a new builtin, which can be a shared object that calls setuid() and therefore regains privileges. However, binaries running with an effective UID of 0 are unaffected.
A heap-based buffer overflow exists in GNU Bash before 4.3 when wide characters, not supported by the current locale set in the LCCTYPE environment variable, are printed through the echo built-in function. A local attacker, who can provide data to print through the "echo -e" built-in function, may use this flaw to crash a script or execute code with the privileges of the bash process. This occurs because ansicstr() in lib/sh/strtrans.c mishandles u32cconv().
Bash could allow a remote authenticated attacker to execute arbitrary commands on the system, caused by the failure to prevent the shell user from modifying BASHCMDS in the rbash. By modifying BASHCMDS, an attacker could exploit this vulnerability to execute arbitrary commands on the system with the permissions of the shell.
The path autocompletion feature in Bash 4.4 allows local users to gain privileges via a crafted filename starting with a " (double quote) character and a command substitution metacharacter.
Bash before 4.4 allows local users to execute arbitrary commands with root privileges via crafted SHELLOPTS and PS4 environment variables.
A vulnerability was found in a way bash expands the $HOSTNAME. Injecting the hostname with malicious code would cause it to run each time bash expanded \h in the prompt string.
References:
http://seclists.org/oss-sec/2016/q3/528
Ubuntu bug:
https://bugs.launchpad.net/ubuntu/+source/bash/+bug/1507025
A security flaw was found in bash, which could be exploited remotely via applications which parse untrusted user scripts via bash. This flaw is different from CVE-2014-6277, CVE-2014-7169 and CVE-2014-7186.