sudo

In Sudo before 1.9.12p2, the sudoedit (aka -e) feature mishandles extra arguments passed in the user-provided environment variables (SUDO_EDITOR, VISUAL, and EDITOR), allowing a local attacker to append arbitrary entries to the list of files to process. This can lead to privilege escalation. Affected versions are 1.8.0 through 1.9.12.p1. The problem exists because a user-specified editor may contain a "--" argument that defeats a protection mechanism, e.g., an EDITOR='vim -- /path/to/extra/file' value.

Sudo 1.8.0 through 1.9.12, with the crypt() password backend, contains a plugins/sudoers/auth/passwd.c array-out-of-bounds error that can result in a heap-based buffer over-read. This can be triggered by arbitrary local users with access to Sudo by entering a password of seven characters or fewer. The impact could vary depending on the system libraries, compiler, and processor architecture.

Sudo before 1.9.5p2 contains an off-by-one error that can result in a heap-based buffer overflow, which allows privilege escalation to root via "sudoedit -s" and a command-line argument that ends with a single backslash character.

selinux_edit_copy_tfiles in sudoedit in Sudo before 1.9.5 allows a local unprivileged user to gain file ownership and escalate privileges by replacing a temporary file with a symlink to an arbitrary file target. This affects SELinux RBAC support in permissive mode. Machines without SELinux are not vulnerable.

In Sudo before 1.8.26, if pwfeedback is enabled in /etc/sudoers, users can trigger a stack-based buffer overflow in the privileged sudo process. (pwfeedback is a default setting in Linux Mint and elementary OS; however, it is NOT the default for upstream and many other packages, and would exist only if enabled by an administrator.) The attacker needs to deliver a long string to the stdin of getln() in tgetpass.c.

In Sudo through 1.8.29, the fact that a user has been blocked (e.g., by using the ! character in the shadow file instead of a password hash) is not considered, allowing an attacker (who has access to a Runas ALL sudoer account) to impersonate any blocked user. NOTE: The software maintainer believes that this CVE is not valid. Disabling local password authentication for a user is not the same as disabling all access to that user--the user may still be able to login via other means (ssh key, kerberos, etc). Both the Linux shadow(5) and passwd(1) manuals are clear on this. Indeed it is a valid use case to have local accounts that are _only_ accessible via sudo and that cannot be logged into with a password. Sudo 1.8.30 added an optional setting to check the _shell_ of the target user (not the encrypted password!) against the contents of /etc/shells but that is not the same thing as preventing access to users with an invalid password hash

In Sudo through 1.8.29, an attacker with access to a Runas ALL sudoer account can impersonate a nonexistent user by invoking sudo with a numeric uid that is not associated with any user. NOTE: The software maintainer believes that this is not a vulnerability because running a command via sudo as a user not present in the local password database is an intentional feature. Because this behavior surprised some users, sudo 1.8.30 introduced an option to enable/disable this behavior with the default being disabled. However, this does not change the fact that sudo was behaving as intended, and as documented, in earlier versions

There is a possible tty hijacking in shadow 4.x before 4.1.5 and sudo 1.x before 1.7.4 via "su - user -c program". The user session can be escaped to the parent session by using the TIOCSTI ioctl to push characters into the input buffer to be read by the next process.

Sudo through 1.8.29 allows local users to escalate to root if they have write access to file descriptor 3 of the sudo process. This occurs because of a race condition between determining a uid, and the setresuid and openat system calls. The attacker can write "ALL ALL=(ALL) NOPASSWD:ALL" to /proc/#####/fd/3 at a time when Sudo is prompting for a password. NOTE: This has been disputed due to the way Linux /proc works. It has been argued that writing to /proc/#####/fd/3 would only be viable if you had permission to write to /etc/sudoers. Even with write permission to /proc/#####/fd/3, it would not help you write to /etc/sudoers