Glossary term
Sandbox
A sandbox is a restricted, controlled environment where software can run without reaching the rest of a system.
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Exploited vulnerability
VMware ESXi sandbox escape (CVE-2025-22225)
CVE-2025-22225
CVE-2025-22225 is a flaw in VMware ESXi, the hypervisor that runs virtual machines on a server.
- On CISA KEV
- CVE ID
- CVE-2025-22225
- CISA KEV
- Listed
- Affected product
- VMware ESXi (also in VMware Cloud Foundation and Telco Cloud Platform)
- Exploited
- Yes
- Published
- March 2025
In short
CVE-2025-22225 is a flaw in VMware ESXi, the hypervisor that runs virtual machines on a server. An attacker who already controls the VMX process of a virtual machine can write to the host's kernel and break out of the sandbox. It was fixed together with two sibling flaws, CVE-2025-22224 and CVE-2025-22226, which the vendor also says were used in attacks.
- CVECVE-2025-22225
- ProductVMware by Broadcom VMware ESXi (also in VMware Cloud Foundation and Telco Cloud Platform)
- CISA KEVListedKnown Exploited Vulnerabilities
- ExploitedYesin real attacks
- Fix Steps5actions listedPatch every ESXi host · Patch the sibling products
What it allows
An attacker who has privileges inside the VMX process of a virtual machine can trigger an arbitrary write into the host kernel and escape the sandbox. That gives control of the hypervisor and every virtual machine on it. CVSS: 8.2 (NVD, CVSS v3.1; the vendor gives the same 8.2 and rates it Important). The attack needs privileges first, so it is used as a second step after another flaw. The sibling CVE-2025-22224 (a race condition causing an out-of-bounds write, vendor score up to 9.3) lets an administrator of a virtual machine run code as the VMX process on the host. CVE-2025-22226 (out-of-bounds read in HGFS) leaks memory from the VMX process.
Who is affected
Per vendor advisory VMSA-2025-0004, impacted products are VMware ESXi, Workstation Pro and Player, Fusion, Cloud Foundation and Telco Cloud Platform. CVE-2025-22225 itself applies to ESXi, Cloud Foundation and Telco Cloud Platform. Fixed ESXi builds: ESXi80U3d-24585383 and ESXi80U2d-24585300 for 8.0, and ESXi70U3s-24585291 for 7.0. Cloud Foundation 5.x and 4.5.x get an async patch to those ESXi builds. Workstation 17.6.3 and Fusion 13.6.3 fix the sibling flaws.
The vendor published advisory VMSA-2025-0004 on 4 March 2025. It states: "VMware by Broadcom has information to suggest that exploitation of CVE-2025-22225 has occurred in the wild." It says the same for CVE-2025-22224 and CVE-2025-22226. The sources opened here give no date for first exploitation.
CISA added CVE-2025-22225 to its Known Exploited Vulnerabilities (KEV) catalog on 4 March 2025, with a due date of 25 March 2025. The KEV entry flags known use in ransomware campaigns for this CVE. The two siblings were added the same day, and their KEV ransomware flag reads Unknown.
No official source opened here names who exploited it, so no actor is attributed. The vendor says there is no workaround.
What to do
-
Patch every ESXi host
Install ESXi80U3d-24585383 or ESXi80U2d-24585300 on 8.0 and ESXi70U3s-24585291 on 7.0. The vendor lists no workaround, so patching is the only fix.
-
Patch the sibling products
Update Workstation to 17.6.3 and Fusion to 13.6.3. Apply the async patch to Cloud Foundation 5.x and 4.5.x as the vendor describes.
-
Limit admin rights inside virtual machines
The attack starts with privileges inside a virtual machine or its VMX process. Reducing admin access in guests and on the management network cuts the first step.
-
Use the KEV deadline as a reference
CISA set 25 March 2025 as the due date for US federal agencies. Use it as a guide for your own patch target.
-
Detect and hunt
The vendor gives no indicators. Review ESXi host logs and change records for unplanned activity around the VMX process, and check whether any host stayed unpatched after 4 March 2025.
Questions
What is CVE-2025-22225?
It is a flaw in VMware ESXi, the hypervisor that runs virtual machines. An attacker who already has privileges in the VMX process of a virtual machine can write to the host kernel and escape the sandbox, gaining control of the hypervisor and every virtual machine on it.
Is there a workaround for CVE-2025-22225?
No. The vendor lists no workaround, so patching is the only fix. Install ESXi80U3d-24585383 or ESXi80U2d-24585300 on 8.0 and ESXi70U3s-24585291 on 7.0, as described in advisory VMSA-2025-0004.
Was CVE-2025-22225 exploited in attacks?
Yes. The vendor said it has information to suggest exploitation occurred in the wild, and CISA added it to its Known Exploited Vulnerabilities catalog on 4 March 2025, flagging known ransomware use. No official source opened names who exploited it.
Sources
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