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Big Ip Advanced Firewall ManagerApplication · F5

CVE-2015-4638

MEDIUM · 5.0 CVSS v2.0 Published 2015-09-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
59/100
Remediation priority · Elevated
Remotely reachable No privileges 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
The FastL4 virtual server in F5 BIG-IP LTM, AAM, AFM, Analytics, APM, ASM, GTM, Link Controller, and PEM 11.3.0 through 11.5.2 and 11.6.0 through 11.6.0 HF4, BIG-IP Edge Gateway, WebAccelerator, and WOM 11.2.1 through 11.3.0, and BIG-IP PSM 11.2.1 through 11.4.1 allows remote attackers to cause a denial of service (Traffic Management Microkernel restart) via a fragmented packet.

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 confidence

The FastL4 virtual server component in F5 BIG-IP products contains a vulnerability where specially crafted fragmented packets can trigger a denial of service, causing the Traffic Management Microkernel to restart. This affects multiple BIG-IP modules including LTM, AAM, AFM, Analytics, APM, ASM, GTM, Link Controller, and PEM in versions 11.3.0-11.5.2 and 11.6.0-11.6.0 HF4.

MitigationApply the vendor-supplied patch or upgrade to a patched version as specified in F5 advisory K16354. Consider implementing packet filtering at network perimeter to block malicious fragmented packets as a compensating control until patching is feasible.

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 Advanced Firewall ManagerApplication
Affected:= 11.3.0= 11.4.0= 11.4.1= 11.5.0= 11.5.1= 11.5.2= 11.6.0
Big Ip AnalyticsApplication
Affected:= 11.3.0= 11.4.0= 11.4.1= 11.5.0= 11.5.1= 11.5.2= 11.6.0
Big Ip Application Security ManagerApplication
Affected:= 11.3.0= 11.4.0= 11.4.1= 11.5.0= 11.5.1= 11.5.2= 11.6.0
Big Ip Edge GatewayWeb browser
Affected:= 11.2.1= 11.3.0
Big Ip Global Traffic ManagerApplication
Affected:= 11.3.0= 11.4.0= 11.4.1= 11.5.0= 11.5.1= 11.5.2= 11.6.0
Big Ip Link ControllerApplication
Affected:= 11.3.0= 11.4.0= 11.4.1= 11.5.0= 11.5.1= 11.5.2= 11.6.0
Big Ip Local Traffic ManagerApplication
Affected:= 11.3.0= 11.4.0= 11.4.1= 11.5.0= 11.5.1= 11.5.2= 11.6.0
Big Ip Policy Enforcement ManagerApplication
Affected:= 11.3.0= 11.4.0= 11.4.1= 11.5.0= 11.5.1= 11.5.2= 11.6.0

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
Low
Authentication
None
Confidentiality
None
Integrity
None
Availability
Partial

AV:N/AC:L/Au:N/C:N/I:N/A:P

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 GUI under System > Software Management > Software Images. Alternatively, run 'bigstart status mcpd' to confirm the management daemon is running, then check the version displayed in the GUI login screen or via 'tmsh show sys version' output.
    Affected if The version falls within 11.3.0-11.5.2 or 11.6.0-11.6.0 HF4 (for example, 11.5.0, 11.5.1, 11.6.0). Versions outside these ranges (such as 11.5.3 or later, or 11.6.0 HF5 and above) are not affected.
  2. Confirm the LTM module is in use
    Run 'tmsh list sys module' to list all installed BIG-IP modules. Verify that Local Traffic Manager (LTM) is listed as active.
    Affected if LTM is present and active, as the vulnerability exists within the FastL4 virtual server component which is part of LTM.
  3. Identify FastL4 virtual servers
    Run 'tmsh list ltm virtual' to list all virtual servers. Review the output for virtual servers with 'profile fastL4' or 'profile fastl4' specified in their configuration.
    Affected if A virtual server is configured with the FastL4 profile, as this is the specific component containing the vulnerability.
  4. Verify network exposure to external traffic
    Review the virtual server destination addresses from step 3. Check if these are exposed to untrusted networks (public-facing IPs, WAN-facing interfaces) by examining the BIG-IP self IPs and network configuration via 'tmsh list sys self-ip' and 'tmsh list net vlan'.
    Affected if The FastL4 virtual server is reachable from untrusted networks, as the attack requires specially crafted fragmented packets to be sent to the virtual server.

The environment is affected if the installed BIG-IP version is 11.3.0-11.5.2 or 11.6.0-11.6.0 HF4, LTM is active, a FastL4 virtual server is configured, and the virtual server is network-accessible to potential attackers.

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 the vendor-supplied patch or upgrade to a patched version as specified in F5 advisory K16354. Consider implementing packet filtering at network perimeter to block malicious fragmented packets as a compensating control until patching is feasible.

Fix this in Big Ip Advanced Firewall Manager Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,480
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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-2015-4638 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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