# CVE-2026-119742: Nagios XI < 2026R2 OS Command Injection via mibs.php

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

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.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://www.nagios.com/security-disclosures/nagios-xi/2026r2/

## Affected products and versions

- Nagios Enterprises, LLC / Nagios XI: ≥ 0; < 2026R2 (affected, custom). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 8.6 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 7.2 (high); CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-78

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://www.nagios.com/security-disclosures/nagios-xi/2026r2/ (CNA: VulnCheck; release-notes, patch)

- https://www.vulncheck.com/advisories/nagios-xi-2026r2-os-command-injection-via-mibs-php (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-119742; retrieved 2026-11-03; source updated 2026-11-03

Revision: 825bcc9387192ea0408332b5e54b52afdc190f07a8c906e028f87990e4ebfc85

Canonical: https://y2.dev/cve/CVE-2026-119742

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