Description
SFCB (Small Footprint CIM Broker) as used in ESXi has an authentication bypass vulnerability. A malicious actor with network access to port 5989 on ESXi may exploit this issue to bypass SFCB authentication by sending a specially crafted request.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | VMware ESXi and VMware Cloud Foundation | VMware ESXi(7.0 before ESXi70U2-17630552, 6.7 before ESXi670-202103101-SG, 6.5 before ESXi650-202107401-SG) and VMware Cloud Foundation (4.x, 3.x before 3.10.2) | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
GitHub 1 repository
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mreza-en/cve-2021-21994_POC ★ 0 · Aug 15, 2026
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.