Guest admin is enough to break out of VMware Workstation onto the host

Both bugs live in code the host exposes to the guest on purpose. VMXNET3 is VMware's own virtual network adapter for virtual machines ^[3]. HGFS is the feature that lets a guest read files and directories sitting on the physical host ^[5]. Parsing input that originates inside the VM is their job.

The scores invert the reach. CVE-2026-59346 carries a 9.3 but requires the VM to be configured with a VMXNET3 adapter ^[2]. CVE-2026-59347 carries an 8.1 and, per Broadcom's wording, needs nothing beyond local administrative privileges on the virtual machine ^[4]. That is a 1.2-point gap on the scale in favour of the bug with the narrower configuration precondition ^[15]. Neither requires any foothold on the host itself ^[14].

On a malware analysis workstation or a developer sandbox, code running as administrator inside the guest is the expected starting state rather than a hurdle an attacker still has to clear. In that setup, the bug is what separates the sample from the host ^[17]. The sources do not say how many such installations exist, and neither advisory writeup quantifies use cases.

The fix is single-track. Both 25H2 and 26H1 are affected, and both are resolved only in 26H1u1 ^[7], so a 25H2 install does not receive a patch in place; it receives a version move ^[16]. That applies to Workstation on Windows and Linux and to Fusion on macOS ^[6]. Broadcom offers no workaround for either flaw and recommends updating as soon as possible ^[8].

What is public: the advisory, the CVSS scores, and the credits. h4urek with secsys lab and Y² reported the VMXNET3 overflow, as did Stan S working with the TrendAI Zero Day Initiative, independently of one another ^[12]. Yeonghyeon Choi and Tianchu Chen of Tencent Xuanwu Lab reported the HGFS overflow ^[13]. Both reports converge on the same virtual NIC, and that convergence, from two separate research lines working independently, is what suggests a reachable bug class rather than a single lucky crash.

What is not public: any exploitation. Broadcom makes no mention of either issue being used in the wild and says both were reported privately, according to SecurityWeek, which dates the announcement to Thursday ^[10][9]. Set against that, SecurityWeek also counts more than two dozen VMware vulnerabilities currently on CISA's Known Exploited Vulnerabilities list ^[11]. Privately reported VMware flaws have a track record of reappearing as tooling, and the absence of a configuration change to fall back on means the only variable here is how quickly 26H1u1 gets deployed.