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Big Ip Local Traffic ManagerApplication · F5

CVE-2016-9256

HIGH · 7.5 CVSS v3.0 Published 2017-05-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
81/100
Remediation priority · High
Remotely reachable Zero-click

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 · unedited
In F5 BIG-IP 12.1.0 through 12.1.2, permissions enforced by iControl can lag behind the actual permissions assigned to a user if the role_map is not reloaded between the time the permissions are changed and the time of the user's next request. This is a race condition that occurs rarely in normal usage; the typical period in which this is possible is limited to at most a few seconds after the permission change.

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 · high confidence

F5 BIG-IP iControl has a race condition where permission enforcement can lag behind actual user permissions if the role_map isn't reloaded between permission changes and the user's next request. This creates a brief window (seconds) where users may retain access they should no longer have.

MitigationApply F5 security update for BIG-IP 12.1.x to address the race condition in role_map reloading. Monitor for immediate permission changes taking effect after the update.

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 Local Traffic ManagerApplication
Affected:= 12.0.0= 12.1.0= 12.1.1= 12.1.2
Big Ip Application Acceleration ManagerApplication
Affected:= 12.0.0= 12.1.0= 12.1.1= 12.1.2
Big Ip Advanced Firewall ManagerApplication
Affected:= 12.0.0= 12.1.0= 12.1.1= 12.1.2
Big Ip AnalyticsApplication
Affected:= 12.0.0= 12.1.0= 12.1.1= 12.1.2
Big Ip Access Policy ManagerApplication
Affected:= 12.0.0= 12.1.0= 12.1.1= 12.1.2
Big Ip Application Security ManagerApplication
Affected:= 12.0.0= 12.1.0= 12.1.1= 12.1.2
Big Ip Domain Name SystemApplication
Affected:= 12.0.0= 12.1.0= 12.1.1= 12.1.2
Big Ip Link ControllerApplication
Affected:= 12.0.0= 12.1.0= 12.1.1= 12.1.2

CVSS 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
High
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:H/PR:L/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify the installed BIG-IP version
    Run `tmsh show /sys version` or check the BIG-IP web UI (System > Software > Image) to determine the exact version number
    Affected if The installed version is 12.0.0, 12.1.0, 12.1.1, or 12.1.2
  2. Confirm iControl API is enabled
    Check if the iControl REST API service is running via `tmsh show /sys service iControlREST` or by verifying the management interface accepts API requests
    Affected if iControl REST API is exposed and accessible (port 443 or 8443 on the management IP or self IP)
  3. Identify user permission change activity
    Review authentication and authorization logs in /var/log/audit for recent role or permission modifications (such as changes to user roles, partition access, or administrative privilege changes)
    Affected if There are recent user permission or role changes performed in the system

The environment is affected if BIG-IP is running version 12.0.0 through 12.1.2 and iControl is accessible while user permission changes have been made recently.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply F5 security update for BIG-IP 12.1.x to address the race condition in role_map reloading. Monitor for immediate permission changes taking effect after the update.

Fix this in Big Ip Local Traffic Manager Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,790
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2016-9256 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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