Nagios Core / XI Authenticated RCE via Custom-Variable Macro Injection (CVE-2026-48553) | HOL Guard CVE

High · CVSS 7.5CVE-2026-48553

Nagios Core / XI Authenticated RCE via Custom-Variable Macro Injection

Answer in brief

CVE-2026-48553 records a High severity (CVSS 7.5) vulnerability in Nagios Core / XI Authenticated RCE via Custom-Variable Macro Injection. The current sources do not mark it as known exploited. The current feed maps Nagios Enterprises, LLC./Nagios Core (generic), Nagios Enterprises, LLC./Nagios XI (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 12, 2026Updated Sep 8, 2026Source checked Sep 27, 2026First seen by HOL Aug 12, 2026Material review Sep 8, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.5
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Nagios Enterprises, LLC./Nagios Core (generic), Nagios Enterprises, LLC./Nagios XI (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Nagios Enterprises, LLC./Nagios Coregeneric	>=0 <4.5.13	4.5.13
Nagios Enterprises, LLC./Nagios XIgeneric	>=0 <2026R1.5	2026R1.5

Recommended response

Check inventory. Check lockfiles and deployed manifests for Nagios Enterprises, LLC./Nagios Core, Nagios Enterprises, LLC./Nagios XI.
Review the reported fix. Update Nagios Enterprises, LLC./Nagios Core to 4.5.13; Nagios Enterprises, LLC./Nagios XI to 2026R1.5 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 12, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 8, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 12, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.