---
id: CVE-2026-119742
title: Nagios XI < 2026R2 OS Command Injection via mibs.php
summary: >-
  Nagios XI before 2026R2 contains an OS command injection vulnerability in the
  MIB upload feature where the install_mib() function in mibs.php sanitizes
  uploaded filenames with an incomplete character-substitution filter that omits
  semico…
severity: high
cvss: 7.2
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-78
vendor: 'Nagios Enterprises, LLC'
product: Nagios XI
affected:
  - nagios_xi < 2026R2
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-11-03T15:59:04.070564Z'
published: '2026-11-03'
updated: '2026-11-03'
sourceUpdated: '2026-11-03T16:00:18.389Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-119742'
references:
  - url: 'https://www.nagios.com/security-disclosures/nagios-xi/2026r2/'
    label: Release Notes
  - url: >-
      https://www.vulncheck.com/advisories/nagios-xi-2026r2-os-command-injection-via-mibs-php
    label: 'VulnCheck Advisory: Nagios XI < 2026R2 OS Command Injection via mibs.php'
tags:
  - cve.org
epss: 0.04088
epssPercentile: 0.90788
ingestedAt: '2026-11-05T20:33:06.278Z'
---

## Overview

Nagios XI before 2026R2 contains an OS command injection vulnerability in the MIB upload feature where the install_mib() function in mibs.php sanitizes uploaded filenames with an incomplete character-substitution filter that omits semicolons, pipes, and non-space IFS whitespace characters before passing them to a grep command run via exec(). An authenticated administrator can upload a MIB file with a crafted filename using tab characters to bypass the deny-list and pipe to sh via a multipart POST request to mibs.php, resulting in arbitrary OS command execution as the web server user.

## Affected

- `nagios_xi < 2026R2`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.