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Nessus Agent CVE-2021-20117

MEDIUM
2021-09-09 vulnreport@tenable.com
6.7
CVSS 3.1 · NVD
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Vulnerability Assessment

Impact

CVSS score of 6.7 (MEDIUM). Attack characteristics: local attack vector, low complexity, high privileges required, no user interaction not required.

Exploit ScenarioDerived

Successful exploitation could compromise the medium-severity affected system.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAI

Nessus Agent 8.3.0 and earlier was found to contain a local privilege escalation vulnerability which could allow an authenticated, local administrator to run specific executables on the Nessus Agent. Rated medium severity (CVSS 6.7), this vulnerability is low attack complexity.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

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

Nessus Agent 8.3.0 and earlier was found to contain a local privilege escalation vulnerability which could allow an authenticated, local administrator to run specific executables on the Nessus Agent host. This is different than CVE-2021-20118. Affected products include: Tenable Nessus Agent.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 6.7 MEDIUM
AV:L/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
Local
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionNVD

Nessus Agent 8.3.0 and earlier was found to contain a local privilege escalation vulnerability which could allow an authenticated, local administrator to run specific executables on the Nessus Agent host. This is different than CVE-2021-20118.

Threat Intelligence Overview

EPSS Score
0.3%
Top 78% 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 MEDIUM
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
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
Defer
Exploitation· derived
None
System Exposure· derived
Small
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

34
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +34
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Privilege escalation occurs when an attacker leverages flaws in access control mechanisms to gain permissions beyond what they were originally granted.

Affected Products (CPE)NVD

cpe:2.3:a:tenable:nessus_agent:*:*:*:*:*:*:*:*
CVE-2021-3450 HIGH
7.4 Mar 25

The X509_V_FLAG_X509_STRICT flag enables additional security checks of the certificates present in a certificate chain.

CVE-2025-36633 HIGH
8.8 Jun 13

Local privilege escalation vulnerability in Tenable Agent for Windows (versions prior to 10.8.5) that allows non-adminis

CVE-2025-36631 HIGH
8.4 Jun 13

Privilege escalation vulnerability in Tenable Agent for Windows (versions prior to 10.8.5) that allows non-administrativ

CVE-2025-36632 HIGH
7.8 Jun 16

Privilege escalation vulnerability in Tenable Agent for Windows (versions prior to 10.8.5) that allows a non-administrat

CVE-2020-5793 HIGH
7.8 Nov 05

A vulnerability in Nessus versions 8.9.0 through 8.12.0 for Windows & Nessus Agent 8.0.0 and 8.1.0 for Windows could all

CVE-2023-5847 HIGH
7.3 Nov 01

Under certain conditions, a low privileged attacker could load a specially crafted file during installation or upgrade t

CVE-2021-20118 MEDIUM
6.7 Sep 09

Nessus Agent 8.3.0 and earlier was found to contain a local privilege escalation vulnerability which could allow an auth

CVE-2021-20077 MEDIUM
6.7 Mar 19

Nessus Agent versions 7.2.0 through 8.2.2 were found to inadvertently capture the IAM role security token on the local h

CVE-2019-16168 MEDIUM
6.5 Sep 09

In SQLite through 3.29.0, whereLoopAddBtreeIndex in sqlite3.c can crash a browser or other application because of missin

CVE-2026-2026 MEDIUM
6.1 Feb 13

Nessus Agent on Windows systems contains improper file permission controls that allow local authenticated users to trigg

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