CVE-2026-40061: When BIG-IP DNS is provisioned, a vulnerability exists in an undisclosed iControl REST and BIG-IP TMOS Shell (

Routine

HIGH 8.7UPGRADE

CVE-2026-40061 is a high-severity flaw (CVSS 8.7) affecting big-ip domain name system. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

When 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 Supp

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.7 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	High
User interaction	None
EPSS exploit chance	0.2% (top 86%)
CISA exploited list	No
Weakness	CWE-77
Published	2026-05-13
Last modified	2026-10-26

Publisher (CNA): F5 Networks · Vendor: f5

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-13 16:16 UTCPublished CVE record published
2026-10-26 17:10 UTCUpdated Record last modified

f5 big-ip domain name system UPGRADE

Affected: >= 16.1.0 and <= 16.1.6 · >= 17.1.0 and <= 17.1.3 · >= 17.5.0 and <= 17.5.1 · 21.0.0

Fixed in: newer than 17.5.1

Safe to downgrade to: a release before 16.1.0

1. Check installed version

apt-cache policy big-ip-domain-name-system || rpm -q big-ip-domain-name-system || big-ip-domain-name-system --version

2. UPGRADE to newer than 17.5.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade big-ip-domain-name-system

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade big-ip-domain-name-system

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 16.1.0 (Debian / Ubuntu)

apt-cache madison big-ip-domain-name-system sudo apt install big-ip-domain-name-system=<VERSION_BEFORE_16.1.0> sudo apt-mark hold big-ip-domain-name-system

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list big-ip-domain-name-system sudo dnf downgrade big-ip-domain-name-system-<VERSION_BEFORE_16.1.0> sudo dnf versionlock add big-ip-domain-name-system

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-40061?

big-ip domain name system: upgrade to newer than 17.5.1. Exact commands for each OS are on this page.

Is CVE-2026-40061 being exploited?

CVE-2026-40061 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-40061 affect?

CVE-2026-40061 affects big-ip domain name system. Severity is high (CVSS 8.7). When 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

How urgent is CVE-2026-40061?

Priority 34/100. High severity

Software pages

F5 BIG-IP vulnerabilities

Related CVEs

CVE-2026-28758 MEDIUM 4.4 UPGRADE When BIG-IP DNS is provisioned, a vulnerability exists in the gtm_add and bigip_add iControl REST commands tha

References

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