CVE-2026-85014 undici CVE debrief

Who should care

Defenders responsible for Node.js applications using undici versions 7.0.0 through 7.29.1 and 8.0.0 through 8.10.2 should assess exposure. This includes operators, platform administrators, vulnerability management teams, and security teams who manage undici deployments. They should prioritize verification and remediation efforts to prevent potential denial-of-service attacks.

Why it matters

CVE-2026-85014 affects undici's experimental WebSocketStream client, allowing an untrusted server to crash a client with a single abrupt disconnect. Defenders should assess exposure and prioritize verification and remediation.

• Crash of Node.js process due to unclean close of TCP connection
• Potential for denial of service due to process termination
• Need for verification of undici versions in use
• Priority on upgrading to fixed versions

Technical summary

The undici experimental WebSocketStream client crashes the Node.js process when a remote peer closes the TCP connection without a WebSocket close handshake. This occurs because the internal socket-close handler calls abort on the writable stream unconditionally and discards the returned promise. As a result, an untrusted server can crash a client with a single abrupt disconnect, affecting undici versions 7.0.0 through 7.29.1 and 8.0.0 through 8.10.2. Defenders should assess exposure and prioritize verification of undici versions.

Defensive priority

Defenders should assess exposure and prioritize verification of undici versions 7.0.0 through 7.29.1 and 8.0.0 through 8.10.2.

Recommended defensive actions

• Upgrade to undici version 7.29.1 or 8.10.2
• Assess exposure of undici versions 7.0.0 through 7.29.1 and 8.0.0 through 8.10.2
• Verify inventory of affected undici versions
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide details on the vulnerability in undici's experimental WebSocketStream client. Evidence is limited to public sources, and defenders should verify undici versions in use. The vulnerability affects undici versions from 7.0.0 up to 7.29.1 and from 8.0.0 up to 8.10.2. There is no indication of in-the-wild exploitation.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.