Threats / VMware / CVE-2021-22017
CVE-2021-22017
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-09-19
VMware vCenter Server vulnerability
VMware vCenter Server contains an improper URI normalization vulnerability in Rhttproxy that allows attackers to bypass security controls and access restricted resources.
Verdict
Today item — known-exploited.
This vulnerability enables attackers to manipulate URI paths through normalization bypass techniques, potentially leading to unauthorized access to vCenter Server functionality. Active exploitation in the wild underscores the practical risk to virtualization infrastructure.
CISA KEV Yes · 2022-01-104EPSS 0.49177 (verify live)5CVSS 5.3 (CISA)3CISA SSVC Exploitation: active · Automatable: yes · Impact: partial3Exploit Public PoC / detection · nuclei template11
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
75 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-01-10).
Probability (EPSS)
EPSS 0.49177 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N) · Affected: VMware, vCenter Server. Confirm exact fixed builds in the vendor advisory.CVSS — CISA-assigned via the ADP container (CVE.org), version 3.1; the CNA left no metrics, so CISA's own score is used ahead of NVD.
Weakness (CWE)
Mapped to CWE-23 Relative Path Traversal — weakness family: Path traversal / file.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: yes · Technical Impact: partialCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 109 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
Public exploit available
Public exploit tooling is catalogued for this CVE (a public proof-of-concept / detection template). Catalog entries: nuclei template. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft malformed or obfuscated URI paths that exploit inconsistent normalization logic to bypass access controls.
Business
Attackers gain unauthorized access to vCenter Server administrative functions, compromising the security posture of the entire virtualized infrastructure.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I use normalized URI bypass to reach restricted endpoints that should be protected by authentication or authorization checks.
Business
Sensitive virtual machine configurations, credentials, and operational data become exposed to unauthorized parties.
3
Lateral reach — past segmentation narrative 3
Attacker
I leverage this access to enumerate systems, modify configurations, or establish persistence within the virtualization environment.
Business
Organizations face potential data exfiltration, service disruption, and loss of control over critical infrastructure assets.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05
Coverage & confidence
— what we know, and what we don’tEstablished (cited)
Coverage gaps — stated, not hidden
Disclosure & credit2
Catalogued by vmwareCNA
Credited with finding itGeorge Noseevich (@webpentest)finderSergey Gerasimov of SolidLab LLCfinderHynek Petrak of Schneider ElectricfinderOsama Alaa of Malcrovefinder
Found an error? Propose a correction.
A correction is a cited counter-claim — it must cite a source,
gets reviewed by a second human, and is never auto-applied. See the
correction convention and our identity
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