CVE-2026-40423: F5 BIG-IP · Unthrottled Resource Allocation
Affects F5 BIG-IPSource CVE Database V5
Not known to be exploited · CVSS 7.5 High · fixed in 21.0.0.2 : patch F5 BIG-IP soon.
Data as of 29 Oct 2026, 19:04 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 18% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 21.0.0.2, 17.5.1.6, 17.1.3.2
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 13 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade F5 BIG-IP to 21.0.0.2, 17.5.1.6 or 17.1.3.2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| F5BIG-IP | Affected
| Fixed in
|
AI-suggested
If you cannot patch yet, consider limiting or filtering SIP traffic to affected virtual servers if feasible to reduce exposure.
Description
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.