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PatchSiren cyber security CVE debrief

CVE-2026-41956 F5 CVE debrief

CVE-2026-41956 is a high-severity vulnerability in F5 BIG-IP Traffic Management Microkernel. When a classification profile is configured on a UDP virtual server, undisclosed requests can cause the Traffic Management Microkernel (TMM) to terminate. This issue affects multiple F5 BIG-IP products and versions. The Common Vulnerability Scoring System (CVSS) score for this vulnerability is 8.7, indicating a high severity. F5 has provided mitigation guidance for this issue.

Vendor
F5
Product
BIG-IP
CVSS
HIGH 8.7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-13
Original CVE updated
2026-06-24
Advisory published
2026-05-13
Advisory updated
2026-06-24

Who should care

Organizations using F5 BIG-IP products, particularly those with UDP virtual servers configured with classification profiles, should prioritize patching this vulnerability. The vulnerability's high CVSS score and potential for denial-of-service attacks make it a critical concern for network administrators and security teams. Additionally, organizations with F5 BIG-IP versions 16.1.0 through 17.1.3 and 17.5.0 through 17.5.1 are affected and should take immediate action.

Technical summary

The vulnerability exists in the Traffic Management Microkernel (TMM) of F5 BIG-IP products when a classification profile is configured on a UDP virtual server. Undisclosed requests can cause the TMM to terminate, leading to a denial-of-service condition. The issue affects various F5 BIG-IP products, including BIG-IP Access Policy Manager, BIG-IP Advanced Firewall Manager, and others. The CVSS vector for this vulnerability is 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.

Defensive priority

This vulnerability has a high CVSS score of 8.7 and can lead to a denial-of-service condition, making it a high-priority issue for F5 BIG-IP administrators. Immediate patching or mitigation is recommended to prevent potential attacks.

Recommended defensive actions

  • Apply the patches provided by F5 for the affected BIG-IP versions.
  • Implement the mitigation guidance provided by F5, as referenced in K000158038.
  • Conduct an inventory check to identify all affected F5 BIG-IP systems in the environment.
  • Prioritize patching for BIG-IP systems with UDP virtual servers configured with classification profiles.
  • Monitor network traffic and system logs for potential exploitation attempts.

Evidence notes

The CVE-2026-41956 record and NVD detail provide official information about the vulnerability. F5's mitigation guidance is available through their support portal. The vulnerability affects multiple F5 BIG-IP products and versions, as listed in the CVE and NVD records.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-41956 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-41956

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-41956 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-41956

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.