Understanding the Sudo CVE‑2019‑14287 Vulnerability and How to Mitigate It

Recently, a critical vulnerability in the Linux sudo utility (CVE‑2019‑14287) was disclosed. Discovered by security researcher Joe Vennix, the bug allows a user to execute commands as root even when root access is explicitly denied.

The flaw works by specifying a user ID of -1 or 4294967295, both of which are interpreted as 0 (the root UID). It affects sudo versions prior to 1.8.28, especially when the RunAs specification in /etc/sudoers contains the keyword ALL , which permits any user to run commands as any other user.

Red Hat rates the vulnerability with a CVSS score of 7.8 (approximately 8/10), but many experts note that the default configurations of most Linux distributions are not vulnerable. The bug primarily impacts systems with non‑standard sudoers settings that allow broad ALL privileges.

Mitigation steps include installing the sudo 1.8.28 patch (or any later version), temporarily removing all users from the sudoers file while the patch is applied, or editing the sudoers entries to replace ALL with explicit target usernames. Administrators can verify exposure with the following command, which lists any risky sudoers lines: alice myhost = (ALL, !root) /usr/bin/vi If the command produces output, the configuration should be revised to avoid the ALL syntax or to explicitly list allowed users.

Various experts weigh in: Todd Miller (maintainer of the open‑source sudo project) says the bug affects only a small subset of Linux users; Douglas Crawford emphasizes that only systems with atypical sudo configurations are at risk; Vectra’s Chris Morales calls the issue “not very critical”; and SaltStack product manager Mehul Revankar advises checking the sudoers file and updating the package promptly.

Overall, while the vulnerability is serious, its practical impact is limited to specially configured environments, and applying the official patch along with proper sudoers hygiene mitigates the risk.