# CVE-2026-40061: F5 BIG-IP DNS command injection in iControl REST and tmsh

Source: https://junglewise.ai/threats/cve-2026-40061-f5-big-ip-dns-command-injection-in-icontrol-rest-and-tmsh  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-13. Updated: 2026-06-29  
License: CC BY 4.0 with a link back

CVE-2026-40061 · Severity: high · CVSS 8.7 · Published 2026-05-13

A vulnerability in F5 BIG-IP DNS allows high-privileged administrative users to bypass security restrictions and execute unauthorized system commands. This could lead to a complete takeover of the device, potentially allowing an attacker to intercept or manipulate network traffic and disrupt critical naming services. The risk is particularly high for deployments in 'Appliance mode,' where it allows attackers to cross protected security boundaries.

Technologies: [F5 BIG-IP DNS](https://junglewise.ai/threats/technologies/big-ip-dns). Vendors: [F5](https://junglewise.ai/threats/vendors/f5).

## Quick answers

**Is CVE-2026-40061 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-40061 being exploited in the wild.

**How severe is CVE-2026-40061?** High severity, with a CVSS score of 8.7, published 13 May 2026.

**Which products and versions are affected?** F5 BIG-IP DNS 21.0.0, 17.5.0 to 17.5.1, 17.1.0 to 17.1.3, 16.1.0 to 16.1.6, All versions prior to EoTS (End of Technical Support).

**Is there a fix for CVE-2026-40061?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-40061 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-40061?** Check whether you run F5 BIG-IP DNS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A command injection vulnerability (CWE-77) exists in undisclosed iControl REST and BIG-IP TMOS Shell (tmsh) commands when BIG-IP DNS is provisioned. The flaw allows an authenticated attacker with Resource Administrator or Administrator roles to execute arbitrary system commands with higher privileges than intended. In Appliance mode deployments, this specifically enables a security boundary crossing. The attack vector is network-based, though it requires high-level administrative credentials. F5 has released updates for affected versions including 17.x and 16.x branches to mitigate this issue.

## Affected products

- F5 BIG-IP DNS 21.0.0, 17.5.0 to 17.5.1, 17.1.0 to 17.1.3, 16.1.0 to 16.1.6

## Timeline

- 2026-05-13: advisory: Initial advisory published by F5 Networks
- 2026-05-13: disclosed

## References

- [https://my.f5.com/manage/s/article/K000160788](https://my.f5.com/manage/s/article/K000160788)

## Related threats

- [F5 BIG-IP sensitive information disclosure in tmsh command](https://junglewise.ai/threats/cve-2026-42408-f5-big-ip-sensitive-information-disclosure-in-tmsh-command)
- [F5 BIG-IP XPath injection in Configuration utility](https://junglewise.ai/threats/cve-2026-40699-f5-big-ip-xpath-injection-in-configuration-utility)
- [F5 BIG-IP TMM denial of service in DNS cache profile](https://junglewise.ai/threats/cve-2026-39458-f5-big-ip-tmm-denial-of-service-in-dns-cache-profile)
- [F5 BIG-IP privilege escalation in scripted monitors](https://junglewise.ai/threats/cve-2026-32673-f5-big-ip-privilege-escalation-in-scripted-monitors)
- [F5 BIG-IP DNS cleartext password exposure in iControl REST](https://junglewise.ai/threats/cve-2026-28758-f5-big-ip-dns-cleartext-password-exposure-in-icontrol-rest)