CVE-2021-40344Public exploitNetwork attack vector

Administrator command execution via MIME-only PHP upload

Published Oct 26, 2021 · Updated Aug 4, 2024

Unrestricted file upload in Nagios XI 5.8.5 allows remote authenticated users with administrator access to execute commands. The Custom Includes upload_files() path relies on verify_uploaded_file() to allow image MIME types but preserves a .php filename in the web-accessible images directory. Administrator access to the Admin panel is required; invoking the uploaded script runs commands as the Apache service account.

CVSS severity7.2
High
EPSS probability66.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unrestricted file upload in Nagios XI 5.8.5 allows remote authenticated users with administrator access to execute commands. The Custom Includes upload_files() path relies on verify_uploaded_file() to allow image MIME types but preserves a .php filename in the web-accessible images directory. Administrator access to the Admin panel is required; invoking the uploaded script runs commands as the Apache service account.

The record

CVE
CVE-2021-40344
Published
Oct 26, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-434, T1505.003
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Oct 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.2NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
T1505.003Server Software Component: Web Shell

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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