CVE-2026-48553: Nagios Core / XI Authenticated RCE via Custom-Variable Macro Injection
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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Nagios Coreto a version that resolves this vulnerability.Fixed in 4.5.13 - Upgrade
Upgrade
Nagios XIto a version that resolves this vulnerability.Fixed in 2026R1.5 - Configuration
Review all host/service/contact custom-variable definitions and ensure that any custom-variable macro is not referenced in command definitions that are executed via a shell.
Nagios Core/Nagios XI (custom variables in shell-executed commands) Custom-variable macro usage in shell-executed command lines = Avoid referencing custom-variable macros in any shell-executed command line; do not use custom variables in command lines that execute via shell
Event History
Frequently Asked Questions
What is the severity of CVE-2026-48553?
CVE-2026-48553 has a high severity rating of 7.5.
What systems are affected by CVE-2026-48553?
CVE-2026-48553 affects Nagios Core versions prior to 4.5.13 and Nagios XI versions prior to 2026R1.5.
How does CVE-2026-48553 exploit a system?
CVE-2026-48553 allows authenticated remote code execution via custom-variable macro injection through the Nagios Remote Data Processor (NRDP).
How do I fix CVE-2026-48553?
To fix CVE-2026-48553, update Nagios Core to version 4.5.13 or later and Nagios XI to version 2026R1.5 or later.
What kind of impact does CVE-2026-48553 have on a system?
CVE-2026-48553 can lead to unauthorized code execution, potentially compromising the integrity and confidentiality of the system.