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Fencer Intel
high 7.2

CVE-2021-40344 in the critical feed json

An issue was discovered in Nagios XI 5.8.5.

published 5y ago modified 4mo ago also EUVD-2021-27523

cvss
7.2
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
64.8%
EPSS 64.8% chance of exploitation in 30 days, percentile 99.2%
public exploits
0
none known

Summary

An issue was discovered in Nagios XI 5.8.5. In the Custom Includes section of the Admin panel, an administrator can upload files with arbitrary extensions as long as the MIME type corresponds to an image. Therefore it is possible to upload a crafted PHP script to achieve remote command execution.

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Exploit prediction

64.80% chance of exploitation in the next 30 days, higher than 99.2% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • synacktiv.com https://www.synacktiv.com/sites/default/files/2021-10/Nagios_XI_multiple_vulnerabilities_0.pdf referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.2 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.5 AV:N/AC:L/Au:S/C:P/I:P/A:P

Classification

Weakness
  • CWE-434 Unrestricted Upload of File with Dangerous Type

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.