Which versions of F5 BIG-IP are affected by CVE-2026-40423?

F5 BIG-IP versions 16.1.0 through 21.0.0.1 contain a high-severity vulnerability in the Traffic Management Microkernel that allows unauthenticated attackers to crash the service and cause complete…. A patch is available.

F5 BIG-IP CVE-2026-40423

Q: What is the CVSS score of CVE-2026-40423?

CVE-2026-40423 has a CVSS 4.0 base score of 8.7 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.1%.

EUVD-2026-29972 HIGH

Allocation of Resources Without Limits or Throttling (CWE-770)

2026-05-13 f5

GHSA-3f74-cm4w-65c4

Denial Of Service

8.7

CVSS 4.0

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Analysis Updated

May 13, 2026 - 16:31 vuln.today

v2 (cvss_changed)

Re-analysis Queued

May 13, 2026 - 16:22 vuln.today

cvss_changed

CVSS changed

May 13, 2026 - 16:22 NVD

7.5 (HIGH) 8.7 (HIGH)

Analysis Generated

May 13, 2026 - 15:51 vuln.today

CVE Published

May 13, 2026 - 14:12 nvd

HIGH 7.5

DescriptionNVD

When a SIP profile is configured on a virtual server, undisclosed traffic can cause the Traffic Management Microkernel (TMM) to terminate.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

AnalysisAI

Traffic Management Microkernel (TMM) crash in F5 BIG-IP versions 16.1.0 through 21.0.0.1 allows unauthenticated remote attackers to cause complete service disruption when a SIP profile is configured on a virtual server. The vulnerability requires specific configuration (SIP profile deployment) and enables denial of service through undisclosed malformed SIP traffic. …

RemediationAI

Within 24 hours: Identify all BIG-IP instances running versions 16.1.0-21.0.0.1 with SIP profiles configured via administrative console audit. Within 7 days: Apply vendor-released patches to all affected systems prioritizing SIP-enabled instances; test in non-production environment first. …

Analysis

Detailed AI-generated intelligence summary covering attack vector, impact assessment, affected versions, remediation steps, and indicators of compromise.

POChttps://••••••••••.com/exploit

PATCHhttps://••••••••••.com/patch

ADVISORYhttps://••••••••••.com/advisory

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Get intelligence summaries, risk assessment, exploit details, threat intel, and remediation guidance.

CVE-2026-40423 vulnerability details – vuln.today

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F5 BIG-IP CVE-2026-40423

CVSS VectorNVD

Lifecycle Timeline

DescriptionNVD

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RemediationAI

Analysis

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F5 BIG-IP CVE-2026-40423

CVSS VectorNVD

Lifecycle Timeline

DescriptionNVD

AnalysisAI

RemediationAI

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External POC / Exploit Code