{"id":"CVE-2021-21973","kind":"vulnerability","aliases":["CVE-2021-21973"],"related":[],"title":"VMware vCenter Server and Cloud Foundation: VMware vCenter Server and Cloud Foundation Server Side Request Forgery (SSRF) Vulnerability","description":"The vSphere Client (HTML5) contains an SSRF (Server Side Request Forgery) vulnerability due to improper validation of URLs in a vCenter Server plugin. A malicious actor with network access to port 443 may exploit this issue by sending a POST request to vCenter Server plugin leading to information disclosure. This affects: VMware vCenter Server (7.x before 7.0 U1c, 6.7 before 6.7 U3l and 6.5 before 6.5 U3n) and VMware Cloud Foundation (4.x before 4.2 and 3.x before 3.10.1.2).","summary":"VMware vCenter Server and Cloud Foundation contain a server-side request forgery flaw caused by improper URL validation in a vCenter plugin. An attacker can make the server send requests to internal hosts and read back the responses, which discloses information.","severity":"medium","cvss":5.3,"epss":0.88012,"exploited":true,"exploited_at":"2022-03-07T00:00:00+00:00","products":[{"name":"VMware vCenter Server and Cloud Foundation","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["cloud-foundation","exploited","vcenter","vendor","vmware"],"not_affected_if":["unpatched-versions-not-in-use"],"how_to_check":"Check the installed vCenter Server version against the VMware advisory for CVE-2021-21973 (VMSA-2021-0002).","fix":"Apply the VMware update for vCenter Server and Cloud Foundation per vendor instructions (CISA required action).","status":"open","published_at":"2021-02-24T17:15:15+00:00","first_seen_at":"2026-10-23T19:11:52+00:00","triaged_at":"2026-10-23T21:23:55+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"vendor","confidence":0.6,"triage":{"at":"2026-10-23T21:23:55Z","model":"claude-haiku-5-5","output":{"fix":"Apply the VMware update for vCenter Server and Cloud Foundation per vendor instructions (CISA required action).\nunknown","reach":"network","impact":"low","summary":"VMware vCenter Server and Cloud Foundation contain a server-side request forgery flaw caused by improper URL validation in a vCenter plugin. An attacker can make the server send requests to internal hosts and read back the responses, which discloses information.","category":"vendor","who_cares":["vmware","vcenter","cloud-foundation"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Attacker reads internal network resources through the vCenter server","analyst_note":"Confirm affected and fixed vCenter versions and whether the plugin SSRF needs credentials, from the VMware advisory VMSA-2021-0002.","how_to_check":"Check the installed vCenter Server version against the VMware advisory for CVE-2021-21973 (VMSA-2021-0002).\nunknown","needs_analyst":true,"not_affected_if":["unpatched-versions-not-in-use"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000494,"input_tokens":2880,"output_tokens":412,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2021':20A,23A '-21973':21A,24A '3':157C '3.10.1.2':160C '4':152C '4.2':155C '443':111C '6.5':144C,146C '6.7':139C,141C '7':134C '7.0':137C 'access':108C 'actor':105C 'affect':130C 'and':28A 'attack':62B 'back':74B 'caus':52B 'client':82C 'cloud':5A,11A,29A,32B,42B,150C 'cloud-found':31B 'contain':44B,84C 'cve':19A,22A 'disclos':78B 'disclosur':128C 'due':92C 'exploit':34B,113C 'flaw':51B 'forgeri':16A,50B,90C 'foundat':6A,12A,33B,43B,151C 'foundation':30A 'host':71B 'html5':83C 'improp':54B,94C 'inform':79B,127C 'intern':70B 'issu':115C 'lead':125C 'make':64B 'malici':104C 'may':112C 'network':107C 'plugin':60B,102C,124C 'port':110C 'post':119C 'read':73B 'request':15A,49B,68B,89C,120C 'respons':76B 'send':67B,117C 'server':3A,9A,13A,27A,40B,47B,66B,87C,101C,123C,133C 'server-sid':46B 'side':14A,48B,88C 'ssrf':17A,86C 'u1c':138C 'u3l':142C 'u3n':147C 'url':55B,97C 'valid':56B,95C 'vcenter':2A,8A,26A,35B,39B,59B,100C,122C,132C 'vendor':36B 'vmware':1A,7A,25A,37B,38B,131C,149C 'vsphere':81C 'vulner':18A,91C 'x':135C,153C,158C","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-02-24T17:15:15+00:00","kev":{"dateAdded":"2022-03-07","dueDate":"2022-03-21","requiredAction":"Apply updates per vendor instructions.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","cvss_by":"nvd@nist.gov","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2021-21973","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-21973","severity":null,"published_at":"2022-03-07T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:52+00:00","fetched_at":"2026-10-25T11:39:17+00:00","note":null},{"source":"epss","external_id":"CVE-2021-21973","url":"https://api.first.org/data/v1/epss?cve=CVE-2021-21973","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:44+00:00","fetched_at":"2026-10-23T19:13:44+00:00","note":null},{"source":"nvd","external_id":"CVE-2021-21973","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-21973","severity":null,"published_at":"2021-02-24T17:15:15+00:00","modified_at":"2026-06-17T03:36:28+00:00","first_seen_at":"2026-10-23T21:57:35+00:00","fetched_at":"2026-10-23T21:57:35+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}