CVE-2020-36851Public exploitNetwork attack vectorHinoki check available

Internal service access via unrestricted proxy targets

Published Sep 25, 2025 · Updated Sep 25, 2025

SSRF in CORS Anywhere 0.4.4 and earlier allows remote attackers to access internal services through an exposed open proxy. The proxy forwarding component takes the destination URL directly from the request path and sends it without blocking private networks or cloud metadata endpoints. Exploitation requires an internet-reachable instance configured for untrusted origins; responses can disclose internal data and cloud credentials.

CVSS severity9.5
Critical
EPSS probability0.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

SSRF in CORS Anywhere 0.4.4 and earlier allows remote attackers to access internal services through an exposed open proxy. The proxy forwarding component takes the destination URL directly from the request path and sends it without blocking private networks or cloud metadata endpoints. Exploitation requires an internet-reachable instance configured for untrusted origins; responses can disclose internal data and cloud credentials.

The record

CVE
CVE-2020-36851
Published
Sep 25, 2025
Updated
Sep 25, 2025
Vendor
Rob Wu
Product
CORS Anywhere
Classifications
CWE-918, CWE-942, CAPEC-664, T1190, T1552.005
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 25, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 25, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=* <=0.4.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Rob Wu · CORS Anywhereversion=* <=0.4.4

Published CVSS scores

9.5VulnCheckCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
CWE-942Permissive Cross-domain Policy with Untrusted Domains
CAPEC-664Server Side Request Forgery
T1190Exploit Public-Facing Application
T1552.005Unsecured Credentials Cloud Instance Metadata API

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo