Broadcom pushed out a critical security advisory on September 3, 2026, warning that VMware Workstation and VMware Fusion contain two flaws serious enough to let an attacker step outside a virtual machine and run code directly on the host. The advisory, tracked as VMSA-2026-0007, carries a combined CVSS range of 8.1 to 9.3 and lists no workaround for either bug. The only fix is to upgrade.
For a company built on the promise that a virtual machine keeps whatever runs inside it separate from the machine underneath, that is the worst kind of bug. CybersecurityNews first reported the disclosure, noting that successful exploitation would let a local administrator inside a VM break out and execute code on the physical host, the exact scenario virtualization exists to prevent. It is the latest entry in a run of cybersecurity disclosures that has kept vendors and defenders busy through 2026.
What VMSA-2026-0007 Actually Discloses
Broadcom’s own advisory page lists two CVEs under VMSA-2026-0007, both affecting VMware Workstation and VMware Fusion running versions 25H2 and 26H1. The synopsis reads plainly: updates address an integer-overflow vulnerability and a buffer-overflow vulnerability. Broadcom rates the pair Critical overall, with the more severe of the two landing at a CVSS v3 base score of 9.3.
Both products get the same fix. Workstation 26H1u1 and Fusion 26H1u1 close the holes, and Broadcom’s compatibility matrix marks the workaround field for each CVE as “None.” There is no registry tweak, no feature to disable, no configuration change that neutralizes the risk short of installing the patched build.
CVE-2026-59346: The VMXNET3 Integer Overflow
The critical half of the advisory is an integer-overflow flaw in VMXNET3, the paravirtualized network adapter VMware ships in Workstation and Fusion. According to Broadcom’s matrix, a user with local administrative privileges inside a VM configured with a VMXNET3 adapter can trigger the overflow and execute arbitrary code on the host operating system. That is a textbook VM-escape path: the attacker never needs a foothold outside the guest, only local admin rights inside it, which in a shared lab, a contractor’s dev box, or a nested-test environment is not a high bar to clear.
Tenable’s CVE tracker lists CVE-2026-59346 with a published date of September 3, 2026, matching Broadcom’s own timeline. The bug sits in the same device class, VMXNET3, that Broadcom patched a month earlier in a separate advisory, a pattern worth returning to below.
CVE-2026-59347: The HGFS Stack Buffer Overflow
The second bug lives in the Host-Guest File System, the component VMware uses to share folders between a VM and the machine it runs on. Broadcom describes it as a stack-based buffer overflow, rated Important with a CVSS v3 score of 8.1, one notch below Critical. Exploiting it lets code execute on the host in the context of the VMX process, the same process that manages the virtual machine itself.
HGFS is convenient. It is also the kind of feature that gets enabled once during setup and forgotten, which means a lot of Workstation and Fusion installs running shared folders today are exposed without anyone actively deciding to keep the feature on.
Affected Versions and What to Patch
The table below reflects Broadcom’s published compatibility matrix for VMSA-2026-0007.
| Product | Affected Version | CVE | CVSSv3 | Fixed Version | Workaround |
|---|---|---|---|---|---|
| VMware Workstation | 25H2, 26H1 | CVE-2026-59346 | 9.3 (Critical) | 26H1u1 | None |
| VMware Workstation | 25H2, 26H1 | CVE-2026-59347 | 8.1 (Important) | 26H1u1 | None |
| VMware Fusion (macOS) | 25H2, 26H1 | CVE-2026-59346 | 9.3 (Critical) | 26H1u1 | None |
| VMware Fusion (macOS) | 25H2, 26H1 | CVE-2026-59347 | 8.1 (Important) | 26H1u1 | None |
Because both products moved to a free distribution model in late 2024, there is no licensing gate stopping anyone from grabbing the patched build immediately. The friction now is entirely operational: knowing which machines run Workstation or Fusion in the first place, since desktop hypervisors rarely go through the same asset-tracking process as servers.
Checking Your Installed Version
Security teams auditing exposure can pull the installed build number directly from the command line before deciding whether a machine needs the update.
# Windows/Linux - VMware Workstation
vmware -v
# macOS - VMware Fusion
/Applications/VMware\ Fusion.app/Contents/Public/vmrun -v
# Confirm VMware Tools build inside a guest
vmware-toolbox-cmd -vAny result below 26H1u1 on Workstation or Fusion means the host is exposed to both CVE-2026-59346 and CVE-2026-59347 and should be queued for an update, particularly on machines where HGFS shared folders or a VMXNET3 adapter are configured.
Is Anyone Actively Exploiting This?
As of publication, there is no public evidence either CVE has been added to CISA’s Known Exploited Vulnerabilities catalog, and no researcher or vendor report describes active exploitation in the wild. Coverage from CybersecurityNews and Broadcom’s own advisory both describe the flaws as privately reported, with impact framed in terms of what an attacker could do rather than what one has done.
That is not the same as low risk. CISA added seven other actively exploited flaws to its KEV catalog in the same week, a reminder of how fast the gap between disclosure and exploitation has been closing across the industry in 2026. The Hacker News covered that KEV update the same week Broadcom published VMSA-2026-0007, and a VM-escape bug with a public CVE number and a 9.3 score is exactly the kind of flaw that tends to get reverse-engineered from the patch diff within days.
It Fits a Busy Year for CVE Disclosures
VMSA-2026-0007 lands in a year that has already produced an unusually heavy stream of high-severity disclosures across widely used software. Google shipped patches for a sixth actively exploited Chrome zero-day earlier in 2026, and enterprise developer tooling has not been spared either, with a critical authentication bypass in JFrog Artifactory scoring 9.8 on its own advisory. CISA’s own tracking reflects the same trend: the agency’s Known Exploited Vulnerabilities catalog picked up a dozen new entries under a tightened remediation deadline just weeks before Broadcom’s disclosure, and a separate zero-day pair in PaperCut print management software hit an estimated 70,000 organizations before patches landed.
Cloud infrastructure has followed the same pattern. A server-side request forgery bug in MLflow let attackers steal cloud provider credentials before CISA added it to KEV, one more example of how quickly a single CVSS 9-plus bug in widely deployed infrastructure software can move from disclosure to confirmed exploitation. Read against that backdrop, a second Critical VM-escape advisory touching Workstation and Fusion in five weeks looks less like an isolated incident and more like one entry in a longer 2026 ledger of vendors racing patches against researchers and attackers working from the same public CVE data.
A Pattern, Not an Isolated Bug
This is not Broadcom’s first VMXNET3 scare in 2026. A month earlier, VMSA-2026-0006 addressed a cluster of five CVEs across ESX, vCenter, Workstation, and Fusion, including CVE-2026-59310, another VMXNET3 out-of-bounds write rated 9.3 by Broadcom’s own advisory. Third-party trackers such as TridentStack list CVE-2026-59310 with a higher composite score of 9.8 and flag it as actively exploited, though that exploitation claim comes from a KEV-monitoring aggregator rather than Broadcom or CISA directly, so treat the discrepancy as unresolved rather than confirmed.
Two advisories in five weeks, both centered on the same virtual network adapter, point to a structural weak spot in how VMXNET3 handles memory rather than a one-off coding mistake. Security teams that patched VMSA-2026-0006 in August and assumed the VMXNET3 problem was closed need to revisit that assumption now.
Market Impact: A Free Product Broadcom Still Has to Defend
VMware Workstation Pro and Fusion Pro have been free for personal, educational, and commercial use since November 11, 2024, part of Broadcom’s broader restructuring of VMware’s business around its enterprise vSphere and Cloud Foundation subscriptions. That shift came in the middle of a pricing backlash that has not fully died down. CRN reported Forrester analyst Tracy Woo’s assessment that enterprise customers saw pricing changes ranging from 3x to 10x under Broadcom’s new per-core subscription model, and The Register cited Civo research showing 48.7% of VMware customers were considering a change of cloud provider and 44.9% were evaluating open-source alternatives.
Workstation and Fusion sit outside that enterprise subscription fight, but they are still the on-ramp millions of developers and IT staff use to evaluate VMware technology before it ever touches a data center contract. A second critical VM-escape advisory in five weeks does not help Broadcom’s case that the platform is worth staying with, even as the desktop product itself costs nothing.
How VMware Stacks Up Against Rival Hypervisors
None of VMware’s desktop-hypervisor rivals are free of their own escape-class history, but licensing terms and how each vendor handles disclosure differ enough to matter for anyone weighing alternatives after a second Critical advisory in five weeks.
| Hypervisor | Base License Cost | Model | Notes |
|---|---|---|---|
| VMware Workstation/Fusion Pro | Free (since Nov 2024) | Type-2, proprietary | Two Critical VM-escape advisories in five weeks (VMSA-2026-0006, -0007) |
| Oracle VirtualBox | Free | Type-2, GPLv3 (Extension Pack under PUEL) | Commercial use of the Extension Pack requires a separate license |
| Parallels Desktop | $99.99–$149.99/yr | Type-2, proprietary, subscription-first | Pro and Business editions are subscription-only, no perpetual option |
| Proxmox VE | Free (support from €120/socket/yr) | Type-1, AGPLv3 | Subscription buys enterprise repo access and support tickets, not the software itself |
| Microsoft Hyper-V | Bundled with Windows 11 Pro/Enterprise/Education | Type-1 | No separate purchase; unavailable on Windows 11 Home |
The distinction that matters most for security teams is Type-1 versus Type-2. Hyper-V and Proxmox run beneath the host operating system, on the bare metal, which narrows the attack surface a guest can reach compared to Workstation and Fusion, which run as applications on top of a general-purpose OS. That does not make Type-1 hypervisors immune to escape bugs, but it does mean the VMXNET3-style path VMware just patched twice has a structurally smaller blast radius on Hyper-V or Proxmox by design.
Why VM-Escape Bugs Carry Outsized Weight
Most vulnerability classes stay contained to the system they hit. A VM-escape bug breaks the isolation boundary that an entire industry has built products around. Cloud providers rent out virtual machines on the promise that one tenant cannot reach another. Security researchers run malware inside VMs specifically because the sandbox is assumed to hold. Developers spin up disposable test environments assuming a compromised guest cannot touch their host laptop.
Workstation and Fusion are desktop products, not the multi-tenant ESXi hosts that power public clouds, so the blast radius of VMSA-2026-0007 is smaller than a hypothetical ESXi escape would be. But desktop hypervisors are exactly what malware analysts, red teams, and software testers use daily, often while deliberately running untrusted or hostile code inside the guest. A bug that turns “isolated by design” into “isolated until the attacker tries VMXNET3” undercuts the one assumption that entire workflow depends on.
What Security Teams Should Do This Week
- Inventory every machine running VMware Workstation or Fusion, including developer laptops and QA environments that rarely show up in standard asset scans
- Check installed build numbers against 26H1u1 using the commands above and prioritize any host using VMXNET3 adapters or HGFS shared folders
- Disable HGFS shared folders on machines that cannot be patched immediately, even though Broadcom lists no formal workaround, since removing the feature narrows one of the two attack paths
- Restrict local administrator rights inside VMs where possible, since both CVEs require local admin privileges in the guest to trigger
- Watch Broadcom’s advisory page and CISA’s KEV catalog for any status change indicating active exploitation
Historical Context: Broadcom’s Post-Acquisition Security Record
Broadcom closed its acquisition of VMware in November 2023 and spent the following year rebuilding the licensing model from the ground up, killing perpetual licenses and moving enterprise customers to per-core subscriptions. Desktop products went the opposite direction, becoming free. Security disclosure cadence has not slowed down during any of that restructuring. VMSA-2026-0006 in early August and VMSA-2026-0007 in early September mark two Critical-severity advisories touching Workstation and Fusion within roughly five weeks, both rooted in the same class of virtual-device memory-handling bug.
That cadence puts Broadcom’s VMware security team in a position familiar to any vendor maintaining a mature, widely deployed codebase: the low-hanging bugs get found and fixed first, and what is left are the deeper, more structural issues embedded in code that has existed for over a decade. VMXNET3 shipped as VMware’s paravirtualized adapter long before the Broadcom acquisition, and its recurrence across two advisories in the same year suggests the underlying driver code needs more than a patch, it needs a harder look at the whole component.
Predictions: Where This Goes From Here
- Expect a proof-of-concept for CVE-2026-59346 to surface within two to four weeks, given the public CVSS 9.3 score and the pattern of researchers reverse-engineering VMware patch diffs quickly in 2026
- CISA is likely to add at least one of the two CVEs to its KEV catalog within 30 to 60 days if exploitation is confirmed, following the same trajectory as CVE-2026-59310 from VMSA-2026-0006
- Broadcom will likely face renewed scrutiny over VMXNET3’s design given two advisories touching the same component in five weeks, possibly prompting a deeper architectural review rather than another point patch
- Expect increased interest in Type-1 alternatives like Proxmox and Hyper-V among security-conscious developers and researchers who run untrusted code in local VMs as part of their daily workflow
- Enterprise customers already frustrated by post-acquisition licensing changes will likely cite this advisory, alongside VMSA-2026-0006, as further justification for migration plans already underway
The Takeaway
Broadcom did what it was supposed to do here: disclose promptly, ship a fix, and rate the severity honestly at 9.3 rather than downplaying it. There is no evidence of active exploitation, no confirmed KEV listing, and a patched build already available. None of that changes the fact that this is the second Critical VM-escape advisory touching VMware Workstation and Fusion in five weeks, both rooted in the same virtual-device code. Patch first, inventory second, and do not assume the VMXNET3 story ends with this advisory.
Frequently Asked Questions
What is VMSA-2026-0007?
It is Broadcom’s security advisory, published September 3, 2026, disclosing two vulnerabilities in VMware Workstation and VMware Fusion: CVE-2026-59346 (VMXNET3 integer overflow, CVSS 9.3) and CVE-2026-59347 (HGFS stack buffer overflow, CVSS 8.1).
Which VMware Workstation and Fusion versions are affected?
Versions 25H2 and 26H1 of both Workstation and Fusion are affected. Broadcom’s fix ships in version 26H1u1 for both products.
Is there a workaround if I cannot patch immediately?
Broadcom’s advisory lists no official workaround for either CVE. Disabling HGFS shared folders and restricting local admin rights inside guests reduces exposure but does not fully close either vulnerability.
Has CVE-2026-59346 or CVE-2026-59347 been exploited in the wild?
As of publication, there is no public evidence of active exploitation and neither CVE appears in CISA’s Known Exploited Vulnerabilities catalog.
Are VMware Workstation and Fusion still free?
Yes. Both have been free for personal, educational, and commercial use since November 11, 2024, following an earlier personal-use-only free tier introduced in May 2024.
How does this relate to VMSA-2026-0006?
VMSA-2026-0006, published roughly a month earlier, addressed a separate cluster of CVEs across ESX, vCenter, Workstation, and Fusion, including CVE-2026-59310, another VMXNET3-related out-of-bounds write rated Critical. The two advisories point to a recurring weak spot in VMXNET3’s memory handling.
What is the difference between VMware Workstation/Fusion and ESXi in terms of risk?
Workstation and Fusion are desktop, Type-2 hypervisors used on individual machines. ESXi is a Type-1 hypervisor that runs multi-tenant production and cloud workloads. A VM-escape bug in ESXi carries a far larger blast radius than the same bug class in a desktop product, though both matter.
Should I switch to a different hypervisor because of this bug?
Not necessarily. Every hypervisor vendor has shipped escape-class bugs at some point. The more actionable step is patching promptly, inventorying which machines run Workstation or Fusion, and limiting local admin rights inside guest VMs regardless of which hypervisor you use.
