# cors-anywhere vulnerable to server-side request forgery

Advisory record · `GHSA-r3jv-xfgx-gj24`

- **Identifiers:** `GHSA-r3jv-xfgx-gj24` · `CVE-2020-36851`
- **State:** Confirmed
- **Severity:** CVSS 9.5 Critical
- **Critical:** Yes: CVSS 9+
- **Weakness (CWE):** [CWE-918](https://cwe.mitre.org/data/definitions/918.html) · [CWE-942](https://cwe.mitre.org/data/definitions/942.html)
- **Tags:** [Server-side request forgery (SSRF)](https://agentprime.io/advisories/tag/ssrf.md) · [CWE-942](https://agentprime.io/advisories/tag/cwe-942.md)
- **Published:** 25 Sept 2025
- **Updated:** 4 May 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 25 Sept 2025, 15:30 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Critical

Critical, because:

- CVSS score 9.5: 9.0 or more.

How we decide what’s critical: <https://agentprime.io/advisories/critical.md>

## Affected packages

- `cors-anywhere` (npm): affected `<=0.4.4`; no fixed version yet

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 9.5 Critical, CVSS 4.0: `CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:H`, from CNA (VulnCheck)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0083, the 57th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the GitHub Advisory Database, published 25 Sept 2025. New records show when each source confirmed them.

## Sources

- [GitHub Advisory Database: GHSA-r3jv-xfgx-gj24](https://github.com/advisories/GHSA-r3jv-xfgx-gj24)
- [OSV: GHSA-r3jv-xfgx-gj24](https://osv.dev/vulnerability/GHSA-r3jv-xfgx-gj24)
- <https://github.com/SocketDev/security-research/security/advisories/GHSA-9wmg-93pw-fc3g>
- <https://nvd.nist.gov/vuln/detail/CVE-2020-36851>
- <https://github.com/Rob--W/cors-anywhere/issues/152>
- <https://github.com/Rob--W/cors-anywhere/issues/521>
- <https://github.com/Rob--W/cors-anywhere/issues/78>
- <https://github.com/Rob--W/cors-anywhere>
- <https://www.certik.com/resources/blog/cors-anywhere-dangers-of-misconfigured-third-party-software>
- <https://www.vulncheck.com/advisories/rob-w-cors-anywhere-misconfigured-cors-proxy-allows-ssrf>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-r3jv-xfgx-gj24>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-r3jv-xfgx-gj24/>. Everything for agents: <https://agentprime.io/llms.txt>.