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Nagios Xi CVE-2021-3277

HIGH
Unrestricted Upload of File with Dangerous Type (CWE-434)
2021-06-07 cve@mitre.org
7.2
CVSS 3.1 · NVD
View

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V5 - File Handling File type validation, storage isolation
MITRE ATT&CK

2 techniques across 2 tactics: Command and Control, Persistence

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 7.2 (HIGH). Attack characteristics: network attack vector, low complexity, high privileges required, no user interaction not required.

Exploit ScenarioDerived

A remote attacker could upload malicious files that can be executed on the server by sending crafted requests to the affected application.

This Week Schedule remediation this week. Why: HIGH severity + EPSS > 10%.
No patch listed yet 54.6% exploitation probability (EPSS)

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AnalysisAI

Nagios XI 5.7.5 and earlier allows authenticated admins to upload arbitrary files due to improper validation of the rename functionality in custom-includes component, which leads to remote code. Rated high severity (CVSS 7.2), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Validate file types server-side, store uploads outside webroot, use random filenames, scan for malware.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Unrestricted File Upload (CWE-434), which allows attackers to upload malicious files that can be executed on the server. Nagios XI 5.7.5 and earlier allows authenticated admins to upload arbitrary files due to improper validation of the rename functionality in custom-includes component, which leads to remote code execution by uploading php files. Affected products include: Nagios Nagios Xi.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 7.2 HIGH
AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionNVD

Nagios XI 5.7.5 and earlier allows authenticated admins to upload arbitrary files due to improper validation of the rename functionality in custom-includes component, which leads to remote code execution by uploading php files.

Threat Intelligence Overview

EPSS Score
54.6%
Top 1% exploitable
Data Quality
2 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 54.6%
Patch available No
Active threat No
Deciding rule
HIGH severity + EPSS > 10%
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

91
Low Medium High Critical
KEV: 0
EPSS: +55
CVSS: +36
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Malicious file upload attacks exploit insufficient validation when web applications accept user-provided files.

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

Affected Products (CPE)NVD

cpe:2.3:a:nagios:nagios_xi:*:*:*:*:*:*:*:*
CVE-2021-25298 HIGH POC
8.8 Feb 15

Nagios XI version xi-5.7.5 is affected by OS command injection. Rated high severity (CVSS 8.8), this vulnerability is re

CVE-2021-25296 HIGH POC
8.8 Feb 15

Nagios XI version xi-5.7.5 is affected by OS command injection. Rated high severity (CVSS 8.8), this vulnerability is re

CVE-2021-25297 HIGH POC
8.8 Feb 15

Nagios XI version xi-5.7.5 is affected by OS command injection. Rated high severity (CVSS 8.8), this vulnerability is re

CVE-2021-25299 MEDIUM POC
6.1 Feb 15

Nagios XI version xi-5.7.5 is affected by cross-site scripting (XSS). Rated medium severity (CVSS 6.1), this vulnerabili

CVE-2018-15708 CRITICAL POC
9.8 Nov 14

Snoopy 1.0 in Nagios XI 5.5.6 allows remote unauthenticated attackers to execute arbitrary commands via a crafted HTTP r

CVE-2018-8734 CRITICAL POC
9.8 Apr 18

SQL injection vulnerability in the core config manager in Nagios XI 5.2.x through 5.4.x before 5.4.13 allows an attacker

CVE-2018-8733 CRITICAL POC
9.8 Apr 18

Authentication bypass vulnerability in the core config manager in Nagios XI 5.2.x through 5.4.x before 5.4.13 allows an

CVE-2021-37343 HIGH POC
8.8 Aug 13

A path traversal vulnerability exists in Nagios XI below version 5.8.5 AutoDiscovery component and could lead to post au

CVE-2019-15949 HIGH POC
8.8 Sep 05

Nagios XI before 5.6.6 allows remote command execution as root. Rated high severity (CVSS 8.8), this vulnerability is re

CVE-2018-8736 HIGH POC
8.8 Apr 18

A privilege escalation vulnerability in Nagios XI 5.2.x through 5.4.x before 5.4.13 allows an attacker to leverage an RC

CVE-2018-8735 HIGH POC
8.8 Apr 18

Remote command execution (RCE) vulnerability in Nagios XI 5.2.x through 5.4.x before 5.4.13 allows an attacker to execut

CVE-2013-6875 HIGH POC
7.5 Nov 26

SQL injection vulnerability in functions/prepend_adm.php in Nagios Core Config Manager in Nagios XI before 2012R2.4 allo

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