CVE-2026-19534

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 67% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — Patch released this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

A fix is available — apply it.

undici's WebSocket client crashes the whole Node.js process during the opening handshake when a server responds with a subprotocol that the client never requested. A default WebSocket connection sends no subprotocol, but if the server's 101 response includes a Sec-WebSocket-Protocol header, undici dereferences a null value while checking it against the requested list and throws an uncaught TypeError. Because that code runs inside a microtask with no surrounding error handling, the exception propagates and terminates the process under Node's default behavior, instead of gracefully failing the connection as required by the WebSocket protocol. Any application that opens a WebSocket to an attacker-controlled or compromised server, or over a plaintext connection subject to a machine-in-the-middle, can be crashed remotely without authentication in the default configuration. This affects undici versions from 6.7.0 up to 6.28.1, from 7.0.0 up to 7.29.1, and from 8.0.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
33%
KEV
Not listed

Published

September 4, 2026

Last Modified

September 8, 2026

Advisory Details (2)

Auto-updated Sep 4, 2026
Patch available. Sources: github.
generic

Security Advisories | OpenJS Foundation CVE Numbering Authority

https://cna.openjsf.org/security-advisories.html
github Patch Available

undici vulnerable to Denial of Service via unrequested WebSocket subprotocol · Advisory · nodejs/undici · GitHub

https://github.com/nodejs/undici/security/advisories/GHSA-rfgv-xxqx-mfg5

Vendor Advisories for CVE-2026-19534(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatgrafana12-4-main-12.4.10-0.2.hum12026-09-09redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
node-undici5.15.0+dfsg1+~cs20.10.9.3-1 ... 8.9.0+dfsg+~cs3.2.0-1 (39 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
node-undici7.15.0+dfsg+~cs3.2.0-1 ... 8.9.0+dfsg+~cs3.2.0-1 (15 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
node-undici7.15.0+dfsg+~cs3.2.0-1 ... 8.9.0+dfsg+~cs3.2.0-1 (15 versions)——

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 16× in last 7d / 20× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-11 16:20 UTCEG score recompute
  2. 2026-09-11 16:20 UTCVendor advisory
  3. 2026-09-11 14:52 UTCEPSS rescore
  4. 2026-09-11 09:36 UTCEPSS rescore
  5. 2026-09-11 04:56 UTCVendor advisory
  6. 2026-09-10 17:32 UTCEG score recompute
  7. 2026-09-10 17:32 UTCVendor advisory
  8. 2026-09-10 09:34 UTCEPSS rescore
  9. 2026-09-10 06:08 UTCVendor advisory
  10. 2026-09-09 07:20 UTCEG score recompute
  11. 2026-09-08 22:00 UTCEPSS rescore
  12. 2026-09-08 03:16 UTCEG score recompute
  13. 2026-09-07 16:01 UTCEPSS rescore
  14. 2026-09-06 17:00 UTCEG score recompute
  15. 2026-09-06 13:47 UTCEPSS rescore
  16. 2026-09-05 18:11 UTCEG score recompute
  17. 2026-09-04 19:19 UTCEG score recompute
  18. 2026-09-04 18:38 UTCEG score recompute
  19. 2026-09-04 17:20 UTCEG score recompute
  20. 2026-09-04 17:19 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-19534?
CVE-2026-19534 is a high vulnerability published on September 4, 2026. undici's WebSocket client crashes the whole Node.js process during the opening handshake when a server responds with a subprotocol that the client never requested. A default WebSocket connection sends no subprotocol, but if the server's 101 response includes a Sec-WebSocket-Protocol header, undici…
When was CVE-2026-19534 disclosed?
CVE-2026-19534 was first published in the National Vulnerability Database on September 4, 2026, with the most recent update on September 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-19534 actively exploited?
CVE-2026-19534 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 67.1% of all scored CVEs.
What is the CVSS score of CVE-2026-19534?
CVE-2026-19534 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-19534?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-19534, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-19534

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