# undici vulnerable to Denial of Service via WebSocketStream unclean close

Advisory record · `GHSA-rx4f-c7p8-82vq`

- **Identifiers:** `GHSA-rx4f-c7p8-82vq` · `CVE-2026-85014`
- **State:** Confirmed
- **Severity:** CVSS 5.9 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-248](https://cwe.mitre.org/data/definitions/248.html) · [CWE-754](https://cwe.mitre.org/data/definitions/754.html)
- **Tags:** [CWE-248](https://agentprime.io/advisories/tag/cwe-248.md) · [CWE-754](https://agentprime.io/advisories/tag/cwe-754.md)
- **Published:** 29 Sept 2026
- **Updated:** 29 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 29 Sept 2026, 18:10 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `undici` (npm): affected `>=7.0.0, <7.29.1 || >=8.0.0, <8.10.2`; fixed in `7.29.1`, `8.10.2`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> The undici npm package, versions 7.0.0 up to 7.29.1 and 8.0.0 up to 8.10.2, has a flaw in its WebSocketStream API that can crash the client process. When a WebSocket connection closes abruptly without a close handshake, an unobserved promise rejection occurs, which under Node.js defaults terminates the process. A malicious or compromised WebSocket server can trigger this with a single connection teardown, and the issue affects applications that write through a writer. Upgrade to undici 7.29.1 or 8.10.2; no workaround is listed.

Written 31 Oct 2026.

## 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

- 5.9 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H`, from CNA (openjs)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0037, the 30th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 13:34 UTC: First seen by agentprime
- 31 Oct 2026, 13:34 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-rx4f-c7p8-82vq)

## Sources

- [GitHub Advisory Database: GHSA-rx4f-c7p8-82vq](https://github.com/advisories/GHSA-rx4f-c7p8-82vq)
- [OSV: GHSA-rx4f-c7p8-82vq](https://osv.dev/vulnerability/GHSA-rx4f-c7p8-82vq)
- <https://github.com/nodejs/undici/security/advisories/GHSA-rx4f-c7p8-82vq>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-85014>
- <https://github.com/nodejs/undici/commit/1858656ebb1e919311c1f31613dfd581b7214349>
- <https://github.com/nodejs/undici/commit/662d0ea671fe64139e79533c913fce412765e1d7>
- <https://cna.openjsf.org/security-advisories.html>
- <https://github.com/nodejs/undici>
- <https://github.com/nodejs/undici/releases/tag/v7.29.1>
- <https://github.com/nodejs/undici/releases/tag/v8.10.2>

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-rx4f-c7p8-82vq>, 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-rx4f-c7p8-82vq/>. Everything for agents: <https://agentprime.io/llms.txt>.