Nagios XI < 2026R2 OS Command Injection via mibs.php
Affects Nagios XI versions before 2026R2 through the MIB upload feature in mibs.php. Fixed in 2026R2.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 2026R2
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Nagios XI versions before 2026R2 The MIB upload feature (install_mib() in mibs.php) is involved
- Exploitation0/40No signal
- Exposure8/25Specific setups only, reachable over the network
- Reach?/20Reach: unknown (data gap). No tracked technology or package matched
- Severity9.6/10CVSS 8.6, total technical impact per CISA
- No patch0/5No signal
What would change the score
- Would score about 68 if added to CISA KEV
- Would score about 63 if CISA's SSVC rates exploitation active
- Would score about 25 if CISA's SSVC rates it automatable
CVE-2026-119742 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.6 (high) and affects Nagios XI; fixed in 2026R2.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 18/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fixed in 2026R2
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
Nagios XI versions before 2026R2 are affected. An authenticated administrator who uploads a MIB file with a specially crafted filename can run arbitrary operating system commands on the server as the web server user.
Read the original description
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.
What to do
Check whether your setup matches what the bug needs.
Nagios XI versions before 2026R2 The MIB upload feature (install_mib() in mibs.php) is involvedUpgrade to a fixed version: 2026R2.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Nagios Enterprises, LLC Nagios XI
fixed in 2026R2
Evidence 2
- Patch
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-119742
Is CVE-2026-119742 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
The install_mib() function in mibs.php, used by the MIB upload feature, lets arbitrary OS commands run as the web server user. The flaw is an OS command injection.Source: vulncheck.com, nagios.com
Which versions are affected by CVE-2026-119742?
Nagios XI: before 2026R2.Source: cve.now feed data
Am I affected, and how do I check?
Nagios XI versions before 2026R2 are affected, and the issue involves the MIB upload feature (install_mib() in mibs.php). To check, look up the installed Nagios XI version and compare it with 2026R2.Source: vulncheck.com, nagios.com
How do I fix CVE-2026-119742?
Upgrade Nagios XI to 2026R2 or later, which is the listed fixed version.Source: vulncheck.com, nagios.com