Nagios Core vulnerabilities

Nagios Core before 4.5.14 and Nagios XI before 2026R1.7 are vulnerable to DOM-based XSS in jsonquery.js, where unencoded JSON string values reflected from stored fields are inserted into the DOM without sanitization, allowing attackers to run arbitrary JavaScript in the victim's browser.

Nagios Core through 4.3.4 initially executes /usr/sbin/nagios as root but supports configuration options in which this file is owned by a non-root account. This allows local users to gain privileges by leveraging access to this non-root account.

In base/logging.c in Nagios Core before version 4.2.4, local users with access to an account in the nagios group can gain root privileges via a symlink attack on the log file. This can also be leveraged by remote attackers using CVE-2016-9565.

MagpieRSS, used in the front-end component in Nagios Core before version 4.2.2, may allow remote attackers to read or write to arbitrary files by spoofing a crafted response from the Nagios RSS feed server.

Nagios Core before 4.5.14 and Nagios XI before 2026R1.7 are vulnerable to authenticated remote code execution via unfiltered NOTIFICATION-family macro substitution through the com_data parameter. When a notification command references $NOTIFICATIONCOMMENT$ or $NOTIFICATIONAUTHOR$ in a shell-reachable position, authenticated UI users can run arbitrary commands as the nagios user. Exploitation requires a non-default configuration in which a notification command references these macros in a shell-executed command line.

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.

Nagios Core before 4.5.14 and Nagios XI before 2026R1.7 contain a cross-site request forgery protection bypass via a self-supplied double-submit cookie. An attacker can supply matching cookie and request parameter values to bypass CSRF protection, enabling unauthenticated attackers to run commands as authorized users via malicious links.

Nagios Core before 4.5.14 and Nagios XI before 2026R1.7 are vulnerable to reflected XSS in cmd.cgi via the NagFormId parameter. An unauthenticated remote attacker can craft a malicious link that, when followed by an authenticated user, executes arbitrary JavaScript in the victim's browser.