Broadcom Patches Critical 'VM Escape' Flaw in VMware ESXi, Plus Four More Vulnerabilities
Five security flaws, three rated critical, have been fixed across VMware's most widely-used virtualisation products. One lets an attacker break out of a contained virtual machine and reach the underlying server it runs on.
Key points
- Broadcom patched five vulnerabilities across VMware ESXi, vCenter, Workstation, and Fusion on Wednesday.
- CVE-2026-47876, rated critical, allows a virtual machine escape: an attacker inside a contained environment can break out and run malicious code on the physical server beneath it.
- CVE-2026-59309 is a critical authentication bypass in vCenter, letting attackers into the management system without a valid password.
- CVE-2026-59310, also critical, lets anyone with basic network access run malicious code on a vCenter server.
- Broadcom says none of the five flaws are being actively exploited yet, but attackers regularly reverse-engineer VMware patches once they're public.
What actually happened here?
Broadcom, which owns VMware, released a security advisory Wednesday covering five flaws across products businesses use to run many virtual computers on a single physical server. A virtual machine is a self-contained computer running inside another computer. The danger with a VM escape is that the walls between that contained space and the real machine underneath break down entirely.
The most serious flaw is CVE-2026-47876. It sits in ESXi, the software layer that manages virtual machines in data centres worldwide, specifically inside the VMXNET3 virtual network adapter, a piece of software that acts like a network card for each virtual machine. An attacker who already has administrator access inside one virtual machine can exploit this to write data outside the memory they're supposed to touch, then execute their own code on the host server. VMware describes this as a VM escape. We covered a similar unauthenticated critical flaw in VMware's Avi Load Balancer in our 14 July story.
The failure mode here is scope. One compromised virtual machine should not reach neighbouring machines or the host. When it can, every other tenant on that server is at risk.
| CVE ID | Product(s) | Severity | What it allows |
|---|---|---|---|
| CVE-2026-47876 | ESXi | Critical | VM escape, run code on host |
| CVE-2026-59309 | vCenter | Critical | Bypass login, unauthorised access |
| CVE-2026-59310 | vCenter | Critical | Run code remotely over network |
| CVE-2026-41703 | ESXi, Workstation, Fusion | High | Leak information or crash host process |
| CVE-2026-41709 | ESXi | Low | Admin actions without audit log entry |
VCenter is the management console businesses use to control all their virtual machines from one place. CVE-2026-59309 lets an attacker skip the password check and walk straight in. CVE-2026-59310 goes a step further: anyone who can reach the vCenter server over a network can run their own code on it, no credentials required.
The high-severity CVE-2026-41703 affects ESXi, Workstation, and Fusion. Someone with VM deployment permissions could use it to extract data or, more realistically, crash the host process, taking everything on that server offline. The low-severity CVE-2026-41709 is narrower: an ESXi admin can take certain actions without those actions appearing in the audit log, useful for covering tracks.
Should ordinary people be worried?
Not directly, but the ripple effect matters. Hospitals, banks, and cloud providers run enormous amounts of their infrastructure on VMware ESXi and vCenter. A successful VM escape at a cloud host could, in the worst case, let attackers move from one customer's environment into another's.
Broadcom says no criminal group is actively using these flaws yet. That window closes fast once patches are published, because attackers routinely reverse-engineer fixes to understand what was broken. The post-mortem will always note the patch existed.
If you receive services from a company running VMware infrastructure, watch for breach notifications over the coming weeks. Running VMware yourself means patching now and confirming vCenter isn't exposed directly to the public internet.
