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CVE-2026-48553

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

7.7 HighFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.97%Up 0.4 points since Aug 13, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.7

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.

Record
CVE-2026-48553
CVSS 4.0
7.7 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-78
Updated
2026-11-02
EUVDEUVD-2026-57345 7.7

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.

Record
EUVD-2026-57345
CVSS 4.0
7.7 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-r6wg-9vj9-rm67 7.7

Nagios Core before 4.5.13 and Nagios XI before 2026R1.5 are vulnerable to authenticated remote...

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.

Record
GHSA-r6wg-9vj9-rm67
CVSS 4.0
7.7 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-78
Updated
2026-11-02
NVD 7.7

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.

Record
CVE-2026-48553
CVSS 4.0
7.7 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-78
Updated
2026-11-02
OSV 7.7

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.

Record
CVE-2026-48553
CVSS 4.0
7.7 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-78
Updated
2026-11-02
OSVDEBIAN-CVE-2026-48553 7.7

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.

Record
DEBIAN-CVE-2026-48553
CVSS 4.0
7.7 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-02
OSVUBUNTU-CVE-2026-48553 7.7

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.

Record
UBUNTU-CVE-2026-48553
CVSS 4.0
7.7 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
nagios4
Debian:12
before 4.4.6-4+deb12u2, plus listed versions
4.4.6-44.4.6-4+deb12u1
4.4.6-4+deb12u2
nagios4
Debian:13
before 4.4.6-4.1+deb13u2, plus listed versions
4.4.6-4.14.4.6-4.1+deb13u1
4.4.6-4.1+deb13u2
nagios4
Debian:14
before 4.5.14+ds-1, plus listed versions
4.4.6-4.14.5.12+ds-1
4.5.14+ds-1
nagios4
Ubuntu:20.04:LTS
All versions, plus listed versions
4.3.4-34.3.4-3ubuntu0.1
None known
nagios4
Ubuntu:22.04:LTS
All versions, plus listed versions
4.4.6-44.4.6-4ubuntu0.22.04.1
None known
nagios4
Ubuntu:24.04:LTS
All versions, plus listed versions
4.4.6-44.4.6-4ubuntu0.24.04.1
None known
nagios4
Ubuntu:26.10
All versions, plus listed versions
4.4.6-4.1ubuntu2
None known
nagios4
Ubuntu:26.04:LTS
All versions, plus listed versions
4.4.6-4.1ubuntu14.4.6-4.1ubuntu2
None known

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-48553 is a high vulnerability (CVSS 7.7) in Nagios Enterprises Xi, published August 12, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.97%, the 61st percentile. Fixed in nagios4 4.4.6-4+deb12u2.

References

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