CVE-2020-36851
CriticalCVSS 9.5Exploitation Probability (EPSS)
Elevated risk56th percentile - higher than 56% of all known CVEs
Summary
Rob--W cors-anywhere instances configured as an open proxy allow unauthenticated external users to induce the server to make HTTP requests to arbitrary targets (SSRF). Because the proxy forwards requests and headers, an attacker can reach internal-only endpoints and link-local metadata services, retrieve instance role credentials or other sensitive metadata, and interact with internal APIs and services not intended to be internet-facing.
Risk Assessment
Successful exploitation can result in theft of cloud credentials, unauthorized access to internal services, remote code execution, privilege escalation, data exfiltration, and full compromise of cloud resources.
Recommendation
Restrict the proxy to trusted origins or authentication, whitelist allowed target hosts, prevent access to link-local and internal IP ranges, remove support for unsafe HTTP methods/headers, and deploy network-level and cloud provider protections.
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Original NVD description (English source)
Rob--W cors-anywhere instances configured as an open proxy allow unauthenticated external users to induce the server to make HTTP requests to arbitrary targets (SSRF). Because the proxy forwards requests and headers, an attacker can reach internal-only endpoints and link-local metadata services, retrieve instance role credentials or other sensitive metadata, and interact with internal APIs and services that are not intended to be internet-facing. The vulnerability is exploitable by sending crafted requests to the proxy with the target resource encoded in the URL; many cors-anywhere deployments forward arbitrary methods and headers (including PUT), which can permit exploitation of IMDSv2 workflows as well as access to internal management APIs. Successful exploitation can result in theft of cloud credentials, unauthorized access to internal services, remote code execution or privilege escalation (depending on reachable backends), data exfiltration, and full compromise of cloud resources. Mitigation includes: restricting the proxy to trusted origins or authentication, whitelisting allowed target hosts, preventing access to link-local and internal IP ranges, removing support for unsafe HTTP methods/headers, enabling cloud provider mitigations, and deploying network-level protections.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS