Decade-Old Sudo Flaw Discovered

Jan 28, 2021

A vulnerability has been discovered in the Linux sudo command that’s been hiding in plain sight.

Sudo is the venerable tool that allows standard users to run admin tasks on Linux distributions. Without sudo, users would have to log into the system as the root user (or change to the root user with the su command), in order to run admin commands. Seeing as how that is looked upon as a security risk, sudo has become a required tool for many Linux admins and users.

However, it has been discovered (by researchers at Qualys) that, for nearly a decade, sudo contained a heap-based buffer overflow vulnerability. This bug could allow any unprivileged user to gain root privileges using the default sudo configuration.

The vulnerability was introduced to sudo in July 2011, by way of commit 8255ed69 and effects the following versions of sudo:

  • Legacy versions from 1.8.2 to 1.8.31p2
  • Stable versions from 1.9.0 to 1.9.5p1

Qualys researchers have been able to verify the vulnerability and even develop multiple exploit variants to obtain full root privileges on Ubuntu 20.04, Debian 1, and Fedora 33.

A new version of sudo (v 1.9.5p2) has been created to patch the vulnerability. It is imperative that all Linux admins and users update their systems (servers and/or desktops) immediately, so their version of sudo is patched.

For more information on this vulnerability, read the official CVE record.

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