What is CVE-2021-40343?

CVE-2021-40343 is a high-severity vulnerability in Nagios Xi, classified under Incorrect Permission Assignment for Critical Resource. CVSS score: 7.8/10. Published 2021-10-26.

How severe is CVE-2021-40343?

High severity. CVSS v3 base score is 7.8 out of 10.

Vulnerability in Nagios Xi

CVE-2021-40343

An issue was discovered in Nagios XI 5.8.5. Insecure file permissions on the nagios_unbundler.py file allow the nagios user to elevate their privileges to the root user.

Published 2021-10-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.007 (49.4th percentile), scored 2026-10-02.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 49th percentile — 49.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: -0.000

Affected products

Nagios Xi — versions 5.8.5

Weakness classification (CWE)

CWE-732 — Incorrect Permission Assignment for Critical Resource

References

assets.nagios.com/downloads/nagiosxi/CHANGES-5.TXT (Release Notes, Vendor Advisory)
synacktiv.com (Not Applicable)
www.synacktiv.com/sites/default/files/2021-10/Nagios_XI_multiple_vulnerabilitie… (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-40343?: CVE-2021-40343 is a high-severity vulnerability in Nagios Xi, classified under Incorrect Permission Assignment for Critical Resource. CVSS score: 7.8/10. Published 2021-10-26.
How severe is CVE-2021-40343?: High severity. CVSS v3 base score is 7.8 out of 10.