{"id":"CVE-2020-3992","published":"2020-10-20T17:15:12Z","modified":"2026-08-12T05:17:31Z","title":"VMware ESXi OpenSLP Use-After-Free Vulnerability","vendor":"VMware","product":"ESXi","tier":"core","eol":null,"description":{"text":"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.","provenance":"source","from":"NVD"},"summary":{"text":"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.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:02:13Z"},"cvss":{"score":9.8,"severity":"CRITICAL","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.83015,"percentile":0.99673,"date":"2026-10-29","provenance":"source"},"kev":{"dateAdded":"2021-11-03","dueDate":"2022-05-03","ransomware":true,"requiredAction":"Apply updates per vendor instructions.","notes":"https://nvd.nist.gov/vuln/detail/CVE-2020-3992","provenance":"source"},"vulncheckKev":{"dateAdded":"2020-11-11","exploitedFirstSeen":"2020-11-11","ransomware":true,"evidence":[{"url":"https://www.rapid7.com/blog/post/2020/11/11/vmware-esxi-openslp-remote-code-execution-vulnerability-cve-2020-3992-and-cve-2019-5544-what-you-need-to-know/","date":"2020-11-11"},{"url":"https://www.cyber.nj.gov/alerts-advisories/ransomware-groups-exploit-vmware-esxi-vulnerabilities","date":"2021-02-04"},{"url":"https://cybersecurityworks.com/blog/ransomware/darkside-the-ransomware-that-brought-a-us-pipeline-to-a-halt.html","date":"2021-05-18"},{"url":"https://securelist.com/it-threat-evolution-q1-2021/102382/","date":"2021-05-31"},{"url":"https://blog.qualys.com/vulnerabilities-threat-research/2021/06/09/darkside-ransomware","date":"2021-06-09"},{"url":"https://cybersecurityworks.com/blog/ransomware/darkside-ransomware-threat-associations-unearthed.html","date":"2021-06-30"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2021-11-03"},{"url":"https://blogs.juniper.net/en-us/threat-research/a-custom-python-backdoor-for-vmware-esxi-servers","date":"2022-12-09"},{"url":"https://www.cert.ssi.gouv.fr/alerte/CERTFR-2023-ALE-015/","date":"2023-02-03"},{"url":"https://www.crowdstrike.com/blog/hypervisor-jackpotting-lack-of-antivirus-support-opens-the-door-to-adversaries/","date":"2023-05-15"}],"evidenceTotal":11,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev | Oct 29, 2026","url":"https://otx.alienvault.com/pulse/6ae20c1db17e7057ae7d9ad1","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 28, 2026","url":"https://otx.alienvault.com/pulse/6ae0ba7e0e2a97ff7b218819","created":"2026-10-27"},{"name":"Actively_Exploited_Kev | Oct 27, 2026","url":"https://otx.alienvault.com/pulse/6adf68b85c3e852f3c111d18","created":"2026-10-26"},{"name":"Actively_Exploited_Kev | Oct 24, 2026","url":"https://otx.alienvault.com/pulse/6adb740e397c3ad4799aa4cd","created":"2026-10-23"},{"name":"Actively_Exploited_Kev | Oct 23, 2026","url":"https://otx.alienvault.com/pulse/6ada236fcfba2dfa730ea482","created":"2026-10-22"},{"name":"Actively_Exploited_Kev | Oct 22, 2026","url":"https://otx.alienvault.com/pulse/6ad8d33a077cbb5cab524d80","created":"2026-10-21"},{"name":"Actively_Exploited_Kev | Oct 21, 2026","url":"https://otx.alienvault.com/pulse/6ad78130c4d1ac2be83a8b6d","created":"2026-10-20"},{"name":"Actively_Exploited_Kev | Oct 20, 2026","url":"https://otx.alienvault.com/pulse/6ad62f63c24a405a3423cc13","created":"2026-10-19"},{"name":"Actively_Exploited_Kev | Oct 19, 2026","url":"https://otx.alienvault.com/pulse/6ad4dda174e5797d0bd238b7","created":"2026-10-18"},{"name":"Actively_Exploited_Kev | Oct 18, 2026","url":"https://otx.alienvault.com/pulse/6ad38c22e1848f8189d1c121","created":"2026-10-17"}],"provenance":"machine"},"cwes":[{"id":"CWE-416","name":"Use After Free"}],"references":[{"url":"https://www.vmware.com/security/advisories/VMSA-2020-0023.html","tags":["Patch","Vendor Advisory"]},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-20-1377/","tags":["Third Party Advisory","VDB Entry"]},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-20-1385/","tags":["Third Party Advisory","VDB Entry"]},{"url":"https://www.vmware.com/security/advisories/VMSA-2020-0023.html","tags":["Patch","Vendor Advisory"]},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-20-1377/","tags":["Third Party Advisory","VDB Entry"]},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-20-1385/","tags":["Third Party Advisory","VDB Entry"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-3992","tags":["US Government Resource"]}],"techniques":[{"id":"T1210","name":"Exploitation of Remote Services","tactics":["lateral-movement"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Network exploitation of OpenSLP service on port 427","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"access to port 427 on an ESXi machine may be able to trigger","start":223,"end":283}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"},{"id":"T1203","name":"Exploitation for Client Execution","tactics":["execution"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: 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fit"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2020-25257","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2020-25257","exploited":true,"exploitedSince":"2021-11-03","provenance":"source"},"exploits":[],"exploitSources":{"pocGithub":{"count":2,"skipped":0,"earliest":"2020-12-01","earliestUrl":"https://github.com/HynekPetrak/CVE-2019-5544_CVE-2020-3992","repos":[{"name":"dgh05t/VMware_ESXI_OpenSLP_PoCs","url":"https://github.com/dgh05t/VMware_ESXI_OpenSLP_PoCs","stars":68,"created":"2021-02-04"},{"name":"HynekPetrak/CVE-2019-5544_CVE-2020-3992","url":"https://github.com/HynekPetrak/CVE-2019-5544_CVE-2020-3992","stars":50,"created":"2020-12-01"}]},"first":{"date":"2020-12-01","source":"PoC-in-GitHub","url":"https://github.com/HynekPetrak/CVE-2019-5544_CVE-2020-3992"},"provenance":"source"},"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1210"],"provenance":"ai"},{"stage":"related","techniques":["T1203"],"provenance":"ai","lowConfidence":true}],"timeline":[{"date":"2020-10-20","kind":"published","label":"Published 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