Review reviewHigh

CVE-2026-42409

F5 BIG-IP, BIG-IP Next SPK, BIG-IP Next CNF

When an HTTP/2 profile and an iRule containing the HTTP::redirect or HTTP::respond command are configured on a virtual server, undisclosed requests can cause the Traffic Management Microkernel (TMM) process to terminate. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

CVSS: 8.7
EPSS: 0.26%
CISA KEV: Not listed
Published: 2026.05.14

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.26%

Technical severityCVSS 8.7

Vulnerability overview

Affected product and versions

Product: F5 BIG-IP, BIG-IP Next SPK, BIG-IP Next CNF
Affected versions: 21.0.0, 17.5.0, 17.1.0, 16.1.0, 2.0.0, 1.7.0, 1.4.0, >= 1.1.0 <= 1.4.0, >= 2.0.0 <= 2.0.2, >= 2.0.0 <= 2.1.0, >= 16.1.0 <= 16.1.6, >= 17.1.0 <= 17.1.3, >= 17.5.0 <= 17.5.1
Fixed versions: No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that F5 BIG-IP, BIG-IP Next SPK, BIG-IP Next CNF and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

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
CWE: CWE-476