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Big Ip Access Policy ManagerApplication · F5

CVE-2020-5926

HIGH · 7.5 CVSS v3.1 Published 2020-08-26
Fix available
A fix is available. Upgrade to 14.1.2.7 / 15.0.1.4 or later.
See remediation →
84/100
Remediation priority · High
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
In BIG-IP versions 15.1.0-15.1.0.4, 15.0.0-15.0.1.3, and 14.1.0-14.1.2.6, a BIG-IP virtual server with a Session Initiation Protocol (SIP) ALG profile, parsing SIP messages that contain a multi-part MIME payload with certain boundary strings can cause TMM to free memory to the wrong cache.

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

This is a memory corruption vulnerability in F5 BIG-IP's SIP ALG (Session Initiation Protocol Application Layer Gateway) profile. When the TMM (Traffic Management Microkernel) parses SIP messages containing multi-part MIME payloads with specific boundary strings, it incorrectly frees memory to the wrong cache, leading to potential memory corruption and potential remote code execution or denial of service.

MitigationDisable the SIP ALG profile on affected virtual servers if not required, and upgrade BIG-IP to a patched version (15.1.0.5, 15.0.1.4, or 14.1.2.7 or later). This is a code-level flaw requiring a software update; configuration changes alone cannot resolve it.

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 Access Policy ManagerApplication
Affected:>= 14.1.0, < 14.1.2.7>= 15.0.0, < 15.0.1.4>= 15.1.0, < 15.1.0.5
Big Ip Advanced Firewall ManagerApplication
Affected:>= 14.1.0, < 14.1.2.7>= 15.0.0, < 15.0.1.4>= 15.1.0, < 15.1.0.5
Big Ip AnalyticsApplication
Affected:>= 14.1.0, < 14.1.2.7>= 15.0.0, < 15.0.1.4>= 15.1.0, < 15.1.0.5
Big Ip Application Acceleration ManagerApplication
Affected:>= 14.1.0, < 14.1.2.7>= 15.0.0, < 15.0.1.4>= 15.1.0, < 15.1.0.5
Big Ip Application Security ManagerApplication
Affected:>= 14.1.0, < 14.1.2.7>= 15.0.0, < 15.0.1.4>= 15.1.0, < 15.1.0.5
Big Ip Domain Name SystemApplication
Affected:>= 14.1.0, < 14.1.2.7>= 15.0.0, < 15.0.1.4>= 15.1.0, < 15.1.0.5
Big Ip Fraud Protection ServiceApplication
Affected:>= 14.1.0, < 14.1.2.7>= 15.0.0, < 15.0.1.4>= 15.1.0, < 15.1.0.5
Big Ip Global Traffic ManagerApplication
Affected:>= 14.1.0, < 14.1.2.7>= 15.0.0, < 15.0.1.4>= 15.1.0, < 15.1.0.5

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

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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. Check BIG-IP version
    Run command 'tmsh show /sys version' or 'tmsh show /sys software' to obtain the installed BIG-IP version
    Affected if The installed version falls within >= 14.1.0 and < 14.1.2.7, or >= 15.0.0 and < 15.0.1.4, or >= 15.1.0 and < 15.1.0.5
  2. Verify SIP ALG profile configuration
    Run 'tmsh list /ltm sip-alg' to list any configured SIP ALG profiles on the system
    Affected if Any SIP ALG profile exists and is in use on virtual servers
  3. Check virtual servers using SIP ALG
    Run 'tmsh list /ltm virtual' and inspect the 'sip-alg' profile association for each virtual server
    Affected if Any virtual server references or enables a SIP ALG profile in its configuration
  4. Confirm TMM processing of SIP traffic
    Inspect traffic logs or run 'tmsh show /ltm profile sip-alg' to verify the SIP ALG profile is actively processing SIP multi-part MIME traffic
    Affected if The SIP ALG profile is actively processing SIP messages containing multi-part MIME payloads with boundary strings

A system is affected if it runs a BIG-IP version in the vulnerable ranges AND has a SIP ALG profile enabled on any virtual server processing SIP traffic.

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
Upgrade available Upgrade to 14.1.2.7 / 15.0.1.4 / 15.1.0.5 or later
Fixed in 14.1.2.715.0.1.415.1.0.5
Interim mitigation

Disable the SIP ALG profile on affected virtual servers if not required, and upgrade BIG-IP to a patched version (15.1.0.5, 15.0.1.4, or 14.1.2.7 or later). This is a code-level flaw requiring a software update; configuration changes alone cannot resolve it.

Fix this in Big Ip Access Policy Manager Scoped from the published advisory
  • Consultation6.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,840
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,144.

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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-2020-5926 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data