Background exploitation KEV catalog No authentication
CVE-2021-22017

VMware vCenter Server Improper Access Control

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…

CheckOps priority index
6.0/10 Patch within 7 days
Severity5.3
Probability4.9
Exploitation4/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 49.2% higher than 98.9% of CVEs
CVSS 3.1 5.3 AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:
Exploited for 1,758 days 10 Jan 2022
CISA due date 24 Jan 2022 for US federal agencies

Exploitation probability EPSS · FIRST

05010026 Sep05 Oct15 Oct24 Oct02 Nov
EPSS probability (%)Percentile among all CVEs

Exploitation signals 4 / 5

  • KEV catalog (CISA)10 Jan 2022
  • Exploited in EUVD (ENISA)10 Jan 2022
  • Used by ransomwareno
  • EPSS above 10 %49.2%
  • No account, over the networkyes

What to do

Fix

Apply the vendor’s fix as soon as it is available.

CISA guidance: Apply updates per vendor instructions.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Description ENISA EUVD

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.

Affected products

VMware vCenter Server, VMware Cloud FoundationvCenter Server
Affected versions
  • VMware vCenter Server(6.7 before 6.7 U3o and 6.5 before 6.5 U3q) and VMware Cloud Foundation 3.x before 3.10.2.2
Weaknesses (CWE)

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

  1. Published

  2. Exploitation reported (ENISA)

  3. Added to the KEV catalog

  4. CISA remediation due date

  5. EPSS peak: 49.2%

References

Other exploited vulnerabilities from the same vendor

  • CVE-2025-22226VMware ESXi, Workstation, and Fusion Information Disclosure Vulnerability
    4.1 · Background exploitation
  • CVE-2025-22225VMware ESXi Arbitrary Write Vulnerability
    5.1 · Background exploitation
  • CVE-2025-22224VMware ESXi and Workstation TOCTOU Race Condition Vulnerability
    5.0 · Background exploitation
  • CVE-2024-38813VMware vCenter Server Privilege Escalation Vulnerability
    5.3 · Background exploitation
  • CVE-2024-38812VMware vCenter Server Heap-Based Buffer Overflow Vulnerability
    8.0 · Background exploitation
  • CVE-2024-37085VMware ESXi Authentication Bypass Vulnerability
    5.9 · Background exploitation

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Sources: CISA KEV · ENISA EUVD · FIRST EPSS · OSV. Public data aggregated by CheckOps, updated automatically. Source texts remain the property of their authors. All exploited vulnerabilities