CVE-2021-3277Network attack vector

Authenticated code execution via unchecked file rename

Published Jun 7, 2021 · Updated Aug 3, 2024

Arbitrary file upload in Nagios XI 5.7.5 and earlier allows remote authenticated admins to execute PHP code on the server. The custom-includes component's rename function accepts uploaded PHP files because it does not adequately validate the renamed file type. Administrative access to the web interface is required, and a successfully renamed script executes arbitrary server-side code.

CVSS severity7.2
High
EPSS probability54.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Arbitrary file upload in Nagios XI 5.7.5 and earlier allows remote authenticated admins to execute PHP code on the server. The custom-includes component's rename function accepts uploaded PHP files because it does not adequately validate the renamed file type. Administrative access to the web interface is required, and a successfully renamed script executes arbitrary server-side code.

The record

CVE
CVE-2021-3277
Published
Jun 7, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-434, T1505.003
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jun 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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 exploitUnconfirmed

Weakness, pattern, technique

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

Public exploit references

No public exploit references are available in this record.

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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