Big Ip Domain Name SystemApplication · F5
CVE-2026-40061
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 · uneditedWhen BIG-IP DNS is provisioned, a vulnerability exists in an undisclosed iControl REST and BIG-IP TMOS Shell (tmsh) command that may allow an authenticated attacker with the Resource Administrator or Administrator role to execute arbitrary system commands with higher privileges. In Appliance mode deployments, a successful exploit can allow the attacker to cross a security boundary. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
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 confidenceThis is an authenticated command injection vulnerability in F5 BIG-IP DNS where an attacker with Resource Administrator or Administrator role can execute arbitrary system commands with elevated privileges via undisclosed iControl REST and tmsh commands. The vulnerability allows privilege escalation beyond the attacker's assigned role permissions.
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
Big Ip Domain Name SystemApplication
>= 16.1.0, <= 16.1.6>= 17.1.0, <= 17.1.3>= 17.5.0, <= 17.5.1= 21.0.0CVSS 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
- Network
- Complexity
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N
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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Confirm BIG-IP DNS module is installedRun 'tmsh show sys module dns' or check 'tmsh list /ltm dns' to verify the DNS module is provisioned and active on the BIG-IP systemAffected if DNS module is not provisioned or the system is not a BIG-IP DNS (it may be a different BIG-IP module like LTM only)
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Check the installed BIG-IP versionRun 'tmsh show /version' or inspect '/etc/product_version' file to obtain the exact BIG-IP version numberAffected if The installed version falls within any of these ranges: 16.1.0-16.1.6, 17.1.0-17.1.3, 17.5.0-17.5.1, or exactly 21.0.0
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Verify iControl REST API is accessibleConfirm the iControl REST endpoint is reachable (typically port 443/tmgmt or port 443 with /mgmt prefix). Check via 'tmsh list /sys httpd' to see REST API settingsAffected if iControl REST interface is enabled and exposed (this is the attack vector required for exploitation)
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Review user accounts with elevated rolesRun 'tmsh list /auth user' to list all local user accounts. Check which accounts have 'Resource Administrator' or 'Administrator' role assignments via 'tmsh list /auth user <username> role'Affected if Any account with Resource Administrator or Administrator role exists on the system (these roles can exploit the vulnerability to escalate beyond their assigned permissions)
The system is potentially affected if it runs BIG-IP DNS with a version in the affected ranges AND has iControl REST accessible AND has at least one user with Resource Administrator or Administrator role.
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.
From vendor dataRestrict access to iControl REST and tmsh interfaces to only essential personnel, apply F5 security patches when available, monitor for suspicious command execution, and ensure least-privilege access controls are enforced.
Fix this in Big Ip Domain Name System
Scoped from the published advisory
- Consultation8.0 h
- Implementation4.0 h
- Testing12.0 h
- Review / QA6.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,320.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-40061 — 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-2026-40061 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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- Version or environment caveats, and links to real fixes
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