VMware ESXi OpenSLP Use-After-Free Vulnerability
VMware · ESXi
VMware ESXi's bundled OpenSLP service contains a use-after-free flaw, which is a memory-safety bug in how the service handles freed memory. An attacker positioned on the management network who can reach port 427 on the ESXi host may be able to trigger the use-after-free and achieve remote code execution, with no authentication or user interaction required.
OpenSLP as used in VMware ESXi (7.0 before ESXi_7.0.1-0.0.16850804, 6.7 before ESXi670-202010401-SG, 6.5 before ESXi650-202010401-SG) has a use-after-free issue. A malicious actor residing in the management network who has access to port 427 on an ESXi machine may be able to trigger a use-after-free in the OpenSLP service resulting in remote code execution.
- Exploited
- Yes, in CISA KEV
- Reports
- 0
- Tactics
- 1/15
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.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 22 days after disclosure. Public exploit code (PoC-in-GitHub) appeared 42 days after disclosure.
- Disclosedday 0
- First seen exploitedVulnCheck KEV evidence+22 days
- Public exploit codePoC-in-GitHub+42 days
- Added to CISA KEVknown ransomware use; EU database agrees+12 mo
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
1 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, 2 cited passages 1Lateral MovementTA0008
Network exploitation of OpenSLP service on port 427
access to port 427 on an ESXi machine may be able to trigger
Lower-confidence links (1)
These come from early or generic mappings, text matching, or contradict this CVE’s details (for example a public-facing technique on a bug that needs a user to open a file). Shown for completeness.
- Exploitation for Client ExecutionT1203 server-side bug exploitable without user interaction; client-execution technique does not fit
Detection
0 rules for this CVE · 15 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-2020-3992 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.
Exploitation of Remote ServicesT121015 general rules
- Zerologon Exploitation Using Well-known Toolscriticalstable
- Audit CVE Eventcriticaltest
- WannaCry Ransomware Activitycriticaltest
- OMIGOD HTTP No Authentication RCE - CVE-2021-38647highstable
- Exploitation Attempt Of CVE-2020-1472 - Execution of ZeroLogon PoChightest
- Exploitation Attempt Of CVE-2023-46214 Using Public POC Codehightest
- HackTool - SharpWSUS/WSUSpendu Executionhightest
- Possible Exploitation of Exchange RCE CVE-2021-42321hightest
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 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
- Actively_Exploited_Kev | Oct 22, 202621 Oct 2026
- 44 more on OTX