The vulnerability stems from the way sudo handles its --chroot (or -R) option, allowing attackers to load arbitrary shared libraries as root if they can control the chroot environment.

To be clear: this is local privilege escalation, not remote code execution. But don’t let that lull you into thinking it’s harmless. If a threat actor or malicious insider already has local access, exploiting this bug is alarmingly straightforward. 

Exploitation has already been demonstrated publicly and could easily be automated. Most major Linux distributions were affected prior to patching, including Ubuntu, Red Hat, Debian, and SUSE.

This post breaks down how the vulnerability works, who it impacts, and what steps you should take to defend against it.

What’s going on inside sudo?

Let’s start with how the --chroot flag is supposed to work. Introduced in sudo 1.9.14, this option allows administrators to run commands within a different root directory – handy for sandboxing or container-like behavior.

Here’s the problem: sudo switches the root before it finishes evaluating its security policy. That means if an attacker can write to the specified chroot directory, they can place fake versions of critical system files there, specifically /etc/nsswitch.conf and malicious shared libraries like libnss_files.so.2.

During execution, sudo loads these files as root, which allows the attacker’s code to run with elevated privileges. From there, a root shell is just a few lines of shell script away.

Who discovered it, and when was it fixed?

Security researcher Rich Mirch reported the flaw and responsibly disclosed it to the sudo maintainers in April 2025. A fix was released in sudo 1.9.17p1 on June 30, 2025, with most major Linux distributions pushing patches shortly afterward.

Interestingly, this bug has existed quietly in the wild since late 2013. It only came to light because someone finally noticed how the order of operations in sudo could be abused.

What makes it so dangerous?

Although it’s not exploitable remotely, a combination of factors makes this vulnerability especially serious:

• The attack is low complexity and requires no special privileges.
• The vulnerable --chroot flag is available by default.
• It provides immediate root access on successful exploitation.
• Proof-of-concept code is already available publicly.

In practical terms, if a malicious actor gains access to a Linux box with a writable directory (like /tmp), they can elevate to root without needing to trick anyone or wait for anything. This is a genuine risk in cloud environments, shared systems, and developer machines.

Proof of concept: A real-world exploit

A working exploit script called sudo-chwoot has been published on GitHub. It uses Docker to demonstrate the full attack chain, from creating a fake root directory to writing malicious config and libraries to popping a root shell.

This makes CVE-2025-32463 not just a theoretical risk, but a very real one. Expect script-kiddie adaptations soon if they’re not already circulating.

How to fix or mitigate it

If your systems run sudo 1.9.14 to 1.9.17, the first thing to do is upgrade immediately to 1.9.17p1 or apply your distro’s backported security patches.

Beyond patching, here are key mitigation steps:

• Disable --chroot support if it’s not required.
• Audit your sudoers policy to ensure only trusted users have access to -R or custom runchroot commands.
• Use file system permissions and mount options (nosuid, noexec, etc.) to harden temp directories and restrict code execution.
• Monitor usage of sudo -R or --chroot in logs and command history – this isn’t a flag you typically see in everyday use.

Who’s affected?

Almost every major Linux distribution had some exposure to this flaw, especially if running recent versions of sudo. Known affected platforms include:

• Ubuntu 22.04, 23.10
• Debian 12
• Red Hat and CentOS 9+
• SUSE Linux Enterprise
• Fedora
• Amazon Linux 2023
• Alpine
• Oracle Linux
• Arch
• Gentoo

macOS also uses sudo, but the default configuration and file system protections may limit exploitability there.

What should security teams do now?

Start by identifying where affected sudo versions are installed in your fleet. Patch aggressively – this isn’t a "wait and see" vulnerability.

Then do the following:

• Scan audit logs for unusual use of sudo -R.
• Tighten permissions on writable directories and restrict shell access where possible.
• If you're using sudo in Docker containers, verify that chroot behavior is isolated properly and not exposed through bind mounts.

SOC teams should also consider deploying detection rules (e.g., Sigma) to raise alerts on unexpected invocations of sudo with -R, particularly in development, CI/CD, and jump box environments.

In summary

CVE-2025-32463 is a perfect example of how complex tools like sudo – even ones we trust implicitly – can become dangerous through subtle misbehaviors. It also reminds us that privilege escalation vulnerabilities don’t have to be flashy to be effective.

This isn’t a vulnerability you can afford to ignore. If you’re responsible for Linux infrastructure, it’s time to patch and lock things down. Privilege escalation is often the missing link in post-compromise attack paths. Don’t let sudo be that link in your environment.

Recommended content

Immersive's Container 7 Research Team recently released a lab dedicated to CVE-2025-32463. This lab includes a vulnerable version of sudo for users to exploit, providing hands-on experience and an in-depth understanding. 

In the lab, you’ll exploit the vulnerability and use it to elevate privileges and capture a token. Read more about it here.