VMware ESXi and Workstation TOCTOU Race Condition Vulnerability
VMware · ESXi and Workstation
A TOCTOU (time-of-check to time-of-use) race condition in VMware ESXi and Workstation can lead to an out-of-bounds write. The flaw lies in the handling of these products' virtual machine components. An attacker who already holds local administrative privileges inside a virtual machine can exploit the flaw to execute code as the VMX process on the host, without user interaction.
VMware ESXi, and Workstation contain a TOCTOU (Time-of-Check Time-of-Use) vulnerability that leads to an out-of-bounds write. A malicious actor with local administrative privileges on a virtual machine may exploit this issue to execute code as the virtual machine's VMX process running on the host.
- Exploited
- Yes, in CISA KEV
- Reports
- 0
- Tactics
- 2/15
How an attack unfolds
Based on MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. mappings. Select a step to see the evidence.How attackers get in
What they do
Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
First seen exploited the day it was disclosed.
CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
2 TechniqueOne specific attacker behaviour in MITRE ATT&CK, such as T1190 “Exploit Public-Facing Application”. IDs with a dot, like T1059.004, are sub-techniques., grouped by TacticThe attacker’s goal at a stage of an attack in MITRE ATT&CK, such as Initial Access or Persistence. Each technique belongs to one or more tactics. in kill-chain order 2Privilege EscalationTA0004
By exploiting the TOCTOU vulnerability in VMWare ESXi, Workstation, and Fusion, an attacker with local admin privileges can execute code in the VMX process on the host, in effect, functioning as an escape from the virtual machine to the host system.
Detection
0 rules for this CVE · 39 general rules for its techniquesRules for this CVE
0Sigma ruleAn open, vendor-neutral detection rule for log data. Security teams convert Sigma rules into searches for their own SIEM. that reference CVE-2025-22224 directly.CVE-specific rules are not available in this build. Search SigmaHQ ↗
General rules for this CVE’s techniques
These detect the technique in general, not this specific vulnerability.
Process InjectionT105537 general rules
- Antivirus PrinterNightmare CVE-2021-34527 Exploit Detectioncriticalstable
- Potential Dridex Activitycriticalstable
- CobaltStrike Named Pipecriticaltest
- CobaltStrike Named Pipe Pattern Regexcriticaltest
- HackTool - DInjector PowerShell Cradle Executioncriticaltest
- Malicious Named Pipe Createdcriticaltest
- RedSun - Named Pipe Createdcriticalexperimental
- RedSun - TieringEngineService.exe Detected as EICAR Test Filecriticalexperimental
Escape to HostT16112 general rules
Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.
What security researchers reported
Not named in any threat report yetAlso mentioned in 50 community threat pulses (AlienVault OTX)
Weaker evidencePulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.
- Actively_Exploited_Kev | Oct 30, 202629 Oct 2026
- Actively_Exploited_Kev | Oct 29, 202628 Oct 2026
- Actively_Exploited_Kev | Oct 28, 202627 Oct 2026
- Actively_Exploited_Kev | Oct 27, 202626 Oct 2026
- Actively_Exploited_Kev | Oct 24, 202623 Oct 2026
- Actively_Exploited_Kev | Oct 23, 202622 Oct 2026
- 44 more on OTX