# ReDoS in Sec-Websocket-Protocol header

Advisory record · `GHSA-6fc8-4gx4-v693`

- **Identifiers:** `GHSA-6fc8-4gx4-v693` · `CVE-2021-32640`
- **State:** Confirmed
- **Severity:** CVSS 5.3 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-345](https://cwe.mitre.org/data/definitions/345.html) · [CWE-400](https://cwe.mitre.org/data/definitions/400.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md) · [CWE-345](https://agentprime.io/advisories/tag/cwe-345.md)
- **Published:** 28 May 2021
- **Updated:** 8 Jul 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 28 May 2021, 19:19 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `ws` (npm): affected `>=7.0.0, <7.4.6 || >=6.0.0, <6.2.2 || >=5.0.0, <5.2.3`; fixed in `7.4.6`, `6.2.2`, `5.2.3`

## 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:N/I:N/A:L`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.028, the 86th percentile, on 12 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 25 May 2021, 17:57 UTC: [Published by the maintainers as a GitHub repository advisory](https://github.com/websockets/ws/security/advisories/GHSA-6fc8-4gx4-v693)

## Sources

- [GitHub Advisory Database: GHSA-6fc8-4gx4-v693](https://github.com/advisories/GHSA-6fc8-4gx4-v693)
- [OSV: GHSA-6fc8-4gx4-v693](https://osv.dev/vulnerability/GHSA-6fc8-4gx4-v693)
- <https://github.com/websockets/ws/security/advisories/GHSA-6fc8-4gx4-v693>
- <https://nvd.nist.gov/vuln/detail/CVE-2021-32640>
- <https://github.com/websockets/ws/issues/1895>
- <https://github.com/websockets/ws/commit/00c425ec77993773d823f018f64a5c44e17023ff>
- <https://github.com/websockets/ws>
- <https://lists.apache.org/thread.html/rdfa7b6253c4d6271e31566ecd5f30b7ce1b8fb2c89d52b8c4e0f4e30@%3Ccommits.tinkerpop.apache.org%3E>
- <https://security.netapp.com/advisory/ntap-20210706-0005>

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-6fc8-4gx4-v693>, 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-6fc8-4gx4-v693/>. Everything for agents: <https://agentprime.io/llms.txt>.