CyberSecBulletin
CVE-2026-39459NVD status: Analyzed

BIG-IP: Least Privilege Violation

Published Updated By the CyberSecBulletin desk

CVE-2026-39459 is a high-severity least privilege violation vulnerability in BIG-IP from F5, with a CVSS 3.1 base score of 7.2 out of 10. It can be exploited remotely over the network by an attacker with administrator privileges, without any action from a user. The record lists versions 21.0.0.2, 17.5.1.6, 17.1.3.2 as the first without the flaw, so updating BIG-IP to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.26% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update BIG-IP to 21.0.0.2 or 17.5.1.6 or 17.1.3.2, whichever matches your release line, or a later version.
  2. Read the advisory on my.f5.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
F5BIG-IP21.0.0 up to, but not including, 21.0.0.2; 17.5.0 up to, but not including, 17.5.1.6; 17.1.0 up to, but not including, 17.1.3.2; 16.1.0 and later21.0.0.2, 17.5.1.6, 17.1.3.2
F5Big-ip Access Policy Manager17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Advanced Firewall Manager17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Advanced Web Application Firewall17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Analytics17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Application Acceleration Manager17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Application Security Manager17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Application Visibility And Reporting17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Automation Toolchain17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Carrier-grade Nat17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Container Ingress Services17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Ddos Hybrid Defender17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Domain Name System17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Edge Gateway17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Fraud Protection Service17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Global Traffic Manager17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Link Controller17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Local Traffic Manager17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Policy Enforcement Manager17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip SSL Orchestrator17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Webaccelerator17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated
F5Big-ip Websafe17.1.0 through 17.1.3; 17.5.0 through 17.5.1; 16.1.0 through 16.1.6; 21.0.0Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
HighAdministrator-level access is required first.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (f5.com).

Scoring systemScoreSeverityScored by
CVSS 4.08.6HighCNA (f5.com)
CVSS 3.17.2HighCNA (f5.com)

Official description

A vulnerability exists in iControl REST and the TMOS Shell (tmsh) where a highly privileged, authenticated attacker with at least the Manager role can create configuration objects that allow running arbitrary commands. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Least Privilege Violation

The elevated privilege level required to perform operations such as chroot() should be dropped immediately after the operation is performed.

How developers prevent this class of flaw

  • Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
  • Follow the principle of least privilege when assigning access rights to entities in a software system.
  • Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

More Least Privilege Violation vulnerabilities (CWE-272)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in BIG-IP

All BIG-IP vulnerabilities

Recent Least Privilege Violation vulnerabilities

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