CVE-2026-48553 Nagios Core / XI Authenticated RCE via Custom-Variable Macro Injection
Authenticated attackers can execute arbitrary OS commands via macro injection in custom variables if referenced in shell commands.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-48553?
CVE-2026-48553 is a high-severity command injection vulnerability in Nagios Core, published on 12 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Nagios Core before 4.5.13 and Nagios XI before 2026R1.5 are vulnerable to authenticated remote code execution via custom-variable macro injection through the Nagios Remote Data Processor (NRDP). When a custom variable defined on a host, service, or contact is referenced in a shell-executed command line, an authenticated attacker with NRDP access can inject OS commands through the macro value. Exploitation requires a non-default configuration in which a custom variable is defined and referenced in a shell-executed command.
Weakness: CWE-78
Which versions are affected by CVE-2026-48553?
How do I fix CVE-2026-48553?
Upgrade to a fixed version.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2026-48553 being exploited?
There is no known exploitation of CVE-2026-48553 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-48553, GHSA-r6wg-9vj9-rm67, UBUNTU-CVE-2026-48553.