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CVE-2021-22017: Rhttproxy as used in vCenter Server contains a vulnerability due to improper implementation of URI normaliz...

Rhttproxy as used in vCenter Server contains a vulnerability due to improper implementation of URI normalization. A malicious actor with network access to port 443 on vCenter Server may exploit this issue to bypass proxy leading to internal endpoints being accessed.

MediumCVSS 5.3Known exploitedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This VMware vCenter Server issue lets an unauthenticated network attacker reach internal endpoints through the HTTPS service because URI normalization is handled incorrectly. The technical severity score is medium, but CISA lists it as known exploited, so exposed legacy vCenter or VMware Cloud Foundation deployments deserve urgent attention.

Executive priority

Prioritize remediation for any reachable vCenter environment because the product is operationally sensitive and CISA lists exploitation. Although the CVSS score is medium, compromise of management-plane visibility or access can carry disproportionate business risk.

Technical view

CVE-2021-22017 affects rhttproxy in VMware vCenter Server and VMware Cloud Foundation. With network access to port 443, an attacker can bypass proxy controls and access internal endpoints. The provided CVSS vector is AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N, indicating unauthenticated remote exposure with limited confidentiality impact.

Likely exposure

Exposure is most likely where vCenter Server 6.7 is before 6.7 U3o, 6.5 is before 6.5 U3q, or VMware Cloud Foundation 3.x is before 3.10.2.2, especially if port 443 is reachable from untrusted networks.

Exploitation context

CISA KEV inclusion indicates known exploitation. The provided sources do not describe exploitation volume, targeting patterns, or exploit mechanics. Treat internet-facing or broadly reachable vCenter management interfaces as higher priority than isolated administrative networks.

Researcher notes

The bundle supports proxy-bypass-to-internal-endpoint access but does not provide CWE mapping, exploit details, or named workarounds. Avoid assuming broader impact than limited confidentiality exposure unless VMware or incident evidence shows chained activity.

Mitigation direction

  • Apply VMware guidance in VMSA-2021-0020 for affected vCenter Server and VMware Cloud Foundation versions.
  • Upgrade vCenter Server 6.7 to 6.7 U3o or later, where applicable.
  • Upgrade vCenter Server 6.5 to 6.5 U3q or later, where applicable.
  • Upgrade VMware Cloud Foundation 3.x to 3.10.2.2 or later, where applicable.
  • Restrict vCenter port 443 access to trusted administrative networks.

Validation and detection

  • Inventory all vCenter Server and VMware Cloud Foundation instances and record versions.
  • Confirm whether vCenter Server 6.7, 6.5, or VCF 3.x versions fall below fixed releases.
  • Check firewall and network policy for untrusted access to vCenter port 443.
  • Review vCenter and proxy logs for unusual access to internal endpoints.
  • Verify remediation against VMware advisory VMSA-2021-0020.
Prepared
Confidence
high
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2021-22017 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.3 (3.1)
Known Exploited
Yes
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
3Source links

CISA KEV status

Status
Known exploited
Source
CISA / ADP
Date added
Not provided

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
5.3CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N3.91.4Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

5.3Medium
CVSS 3.1 vector shape for CVE-2021-22017Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/aVMware vCenter Server, VMware Cloud FoundationVMware vCenter Server(6.7 before 6.7 U3o and 6.5 before 6.5 U3q) and VMware Cloud Foundation 3.x before 3.10.2.2Listed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.