{"id":"UBUNTU-CVE-2026-48553","details":"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.","modified":"2026-08-19T11:05:27Z","published":"2026-08-12T17:17:00Z","upstream":["CVE-2026-48553"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-48553"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-48553"},{"type":"REPORT","url":"https://github.com/NagiosEnterprises/nagioscore/blob/master/Changelog"},{"type":"REPORT","url":"https://www.nagios.com/security-disclosures/nagios-core/"},{"type":"REPORT","url":"https://www.vulncheck.com/advisories/nagios-core-xi-authenticated-rce-via-custom-variable-macro-injection"}],"affected":[{"package":{"name":"nagios4","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/nagios4?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.3.4-3","4.3.4-3ubuntu0.1"],"ecosystem_specific":{"binaries":[{"binary_name":"nagios4","binary_version":"4.3.4-3ubuntu0.1"},{"binary_name":"nagios4-cgi","binary_version":"4.3.4-3ubuntu0.1"},{"binary_name":"nagios4-common","binary_version":"4.3.4-3ubuntu0.1"},{"binary_version":"4.3.4-3ubuntu0.1","binary_name":"nagios4-core"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-48553.json"}},{"package":{"name":"nagios4","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/nagios4?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.4.6-4","4.4.6-4ubuntu0.22.04.1"],"ecosystem_specific":{"binaries":[{"binary_version":"4.4.6-4ubuntu0.22.04.1","binary_name":"nagios4"},{"binary_version":"4.4.6-4ubuntu0.22.04.1","binary_name":"nagios4-cgi"},{"binary_name":"nagios4-common","binary_version":"4.4.6-4ubuntu0.22.04.1"},{"binary_name":"nagios4-core","binary_version":"4.4.6-4ubuntu0.22.04.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-48553.json"}},{"package":{"name":"nagios4","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/nagios4?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.4.6-4","4.4.6-4ubuntu0.24.04.1"],"ecosystem_specific":{"binaries":[{"binary_name":"nagios4","binary_version":"4.4.6-4ubuntu0.24.04.1"},{"binary_name":"nagios4-cgi","binary_version":"4.4.6-4ubuntu0.24.04.1"},{"binary_version":"4.4.6-4ubuntu0.24.04.1","binary_name":"nagios4-common"},{"binary_name":"nagios4-core","binary_version":"4.4.6-4ubuntu0.24.04.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-48553.json"}},{"package":{"name":"nagios4","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/nagios4?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.4.6-4.1ubuntu1","4.4.6-4.1ubuntu2"],"ecosystem_specific":{"binaries":[{"binary_version":"4.4.6-4.1ubuntu2","binary_name":"nagios4"},{"binary_name":"nagios4-cgi","binary_version":"4.4.6-4.1ubuntu2"},{"binary_name":"nagios4-common","binary_version":"4.4.6-4.1ubuntu2"},{"binary_version":"4.4.6-4.1ubuntu2","binary_name":"nagios4-core"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-48553.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}