# CORS misconfiguration in socket.io

Advisory record · `GHSA-fxwf-4rqh-v8g3`

- **Identifiers:** `GHSA-fxwf-4rqh-v8g3` · `CVE-2020-28481`
- **State:** Confirmed
- **Severity:** CVSS 5.3 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-346](https://cwe.mitre.org/data/definitions/346.html) · [CWE-453](https://cwe.mitre.org/data/definitions/453.html)
- **Tags:** [CWE-346](https://agentprime.io/advisories/tag/cwe-346.md) · [CWE-453](https://agentprime.io/advisories/tag/cwe-453.md)
- **Published:** 20 Jan 2021
- **Updated:** 14 Jan 2025
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 20 Jan 2021, 21:22 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `socket.io` (npm): affected `<2.4.0`; fixed in `2.4.0`

## 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

- 5.3 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:P/RL:O/RC:C`, from CNA (snyk)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0075, the 54th 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 20 Jan 2021. New records show when each source confirmed them.

## Sources

- [GitHub Advisory Database: GHSA-fxwf-4rqh-v8g3](https://github.com/advisories/GHSA-fxwf-4rqh-v8g3)
- [OSV: GHSA-fxwf-4rqh-v8g3](https://osv.dev/vulnerability/GHSA-fxwf-4rqh-v8g3)
- <https://nvd.nist.gov/vuln/detail/CVE-2020-28481>
- <https://github.com/socketio/socket.io/issues/3671>
- <https://github.com/socketio/socket.io/commit/f78a575f66ab693c3ea96ea88429ddb1a44c86c7>
- <https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSBOWER-1056358>
- <https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1056357>
- <https://snyk.io/vuln/SNYK-JS-SOCKETIO-1024859>

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-fxwf-4rqh-v8g3>, 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-fxwf-4rqh-v8g3/>. Everything for agents: <https://agentprime.io/llms.txt>.