CVE-2021-20135
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedNessus versions 8.15.2 and earlier were found to contain a local privilege escalation vulnerability which could allow an authenticated, local administrator to run specific executables on the Nessus Agent host. Tenable has included a fix for this issue in Nessus 10.0.0. The installation files can be obtained from the Tenable Downloads Portal (https://www.tenable.com/downloads/nessus).
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceNessus Agent versions 8.15.2 and earlier contain a local privilege escalation vulnerability where an authenticated local administrator can execute specific binaries with elevated privileges on the host system, potentially leading to full system compromise.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 8.15.2CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Verify Nessus Agent installationCheck if Tenable Nessus or Nessus Agent is installed on the system by searching for the application in installed programs or checking for Nessus-related processes runningAffected if Nessus or Nessus Agent is present on the system
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Locate the installed versionUse the system package manager, registry, or application itself to retrieve the exact version number of Nessus Agent (for example, use 'nessuscli --version' or check Add/Remove Programs)Affected if Version cannot be determined or the application is not found
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Compare against affected versionsCompare your installed version to the vulnerable range: any version of Nessus Agent 8.15.2 or earlier is affectedAffected if Installed version is 8.15.2 or lower
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Verify attacker requirementsConfirm whether the current user has authenticated local administrator privileges on the systemAffected if The user has local administrator rights (this is required for the exploit to work)
You are affected if Nessus Agent is installed with version 8.15.2 or earlier and you are running as an authenticated local administrator on that host.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpgrade Nessus Agent to version 10.0.0 or later from the Tenable Downloads Portal to remediate this vulnerability.
Nessus 10.0.0 or later
- 1. Download Nessus 10.0.0 or later from the Tenable Downloads Portal at https://www.tenable.com/downloads/nessus
- 2. Back up your current Nessus configuration and scan data
- 3. Stop the Nessus service
- 4. Install Nessus 10.0.0 or later
- 5. Verify the installation completed successfully
- 6. Start the Nessus service
- 7. Confirm the upgrade resolved the privilege escalation vulnerability
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20135 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-20135 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data