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Fencer Vulns
high 7.5

CVE-2026-19534 json

undici vulnerable to Denial of Service via unrequested WebSocket subprotocol

published 2026-09-04 2 mo ago modified 2026-09-29 40 d ago also EUVD-2026-71636 , GHSA-rfgv-xxqx-mfg5

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 33%
public exploits
0
none known

Summary

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.

Patch / fix

  • npm undici 6.28.1, 7.29.1, 8.10.2
  • undici undici 6.28.1, 7.29.1, 8.10.2
  • node-undici Debian 14 8.10.2+dfsg+~cs3.2.2-1

debian advisories DEBIAN-CVE-2026-19534

  • npm RHEL 9 1:10.9.8-1.22.23.2.2.module+el9.8.0+24958+80b2ac6e
  • nodejs RHEL 9 1:22.23.2-2.module+el9.8.0+24958+80b2ac6e
  • nodejs-libs RHEL 9 1:22.23.2-2.module+el9.8.0+24958+80b2ac6e
  • nodejs-nodemon RHEL 9 3.1.14-2.module+el9.8.0+24709+804d6b5b
  • nodejs-full-i18n RHEL 9 1:22.23.2-2.module+el9.8.0+24958+80b2ac6e
  • nodejs-packaging RHEL 9 2021.06-6.module+el9.8.0+24709+804d6b5b
  • nodejs-packaging-bundler RHEL 9 2021.06-6.module+el9.8.0+24709+804d6b5b
  • nodejs22 RHEL 10.2 1:22.23.2-3.el10_2

red hat advisories RHSA-2026:84589RHSA-2026:84703RHSA-2026:76750RHSA-2026:75864RHSA-2026:75870RHSA-2026:74085

  • npm AlmaLinux 9 1:10.9.8-1.22.23.2.2.module_el9.8.0+322+f4aa738c
  • nodejs AlmaLinux 9 1:22.23.2-2.module_el9.8.0+322+f4aa738c
  • nodejs-libs AlmaLinux 9 1:22.23.2-2.module_el9.8.0+322+f4aa738c
  • nodejs-nodemon AlmaLinux 9 3.1.14-2.module_el9.8.0+302+959ebcd4
  • nodejs-full-i18n AlmaLinux 9 1:22.23.2-2.module_el9.8.0+322+f4aa738c
  • nodejs-packaging AlmaLinux 9 2021.06-6.module_el9.7.0+227+12323393
  • nodejs-packaging-bundler AlmaLinux 9 2021.06-6.module_el9.7.0+227+12323393
  • nodejs AlmaLinux 10 1:22.23.2-3.el10_2

almalinux advisories ALSA-2026:76750ALSA-2026:75864ALSA-2026:75870ALSA-2026:73838ALSA-2026:74085ALSA-2026:73428

  • nodejs Rocky Linux 9 1:22.23.2-2.module+el9.8.0+40374+17512296
  • nodejs-nodemon Rocky Linux 9 3.1.14-2.module+el9.8.0+40280+057606e8
  • nodejs-nodemon Rocky Linux 9 3.1.14-2.module+el9.8.0+40264+d9b257bb
  • nodejs-packaging Rocky Linux 9 2021.06-6.module+el9.7.0+40052+e32ea525
  • nodejs-packaging Rocky Linux 9 2021.06-6.module+el9.7.0+40153+4d595597
  • nodejs-packaging Rocky Linux 9 2021.06-6.module+el9.7.0+40165+d075e3f2
  • nodejs-packaging Rocky Linux 9 2021.06-6.module+el9.8.0+40164+8921ab53
  • nodejs22 Rocky Linux 10 1:22.23.2-3.el10_2

rocky linux advisories RLSA-2026:76750RLSA-2026:75864RLSA-2026:75870RLSA-2026:73428RLSA-2026:74085RLSA-2026:73838

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-19534 updated cvss 7.5

undici: undici: Denial of Service via unrequested WebSocket subprotocol

  • Red Hat Exploit Intelligence exploit-intelligence/vulnerability-analysis-rhel9 Red Hat OpenShift Pipelines openshift-pipelines/pipelines-console-plugin-rhel9, openshift-pipelines/pipelines-console-plugin-pf5-rhel9 Red Hat Build of Podman Desktop rh-podman-desktop.git 1.1.0, rh-podman-desktop a4ea1f988eb28bc86ab3516bba3a4973b252a17e Red Hat Enterprise Linux 9 npm, nodejs, nodejs-libs, nodejs-full-i18n Red Hat Enterprise Linux 10 nodejs26 26.1.0-1.el10
    affected: workaround, no fix available
  • Red Hat Hardened Images nodejs25 25.9.0-1.6.hum1
    affected: workaround, no fix planned “Will not fix”
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-rhel9, rhoai/odh-core-bff-rhel9, rhoai/odh-dashboard-operator-rhel9, rhoai/odh-mod-arch-agent-ops-rhel9 Red Hat OpenShift Container Platform 4 openshift4/ose-monitoring-plugin-rhel9 Red Hat OpenShift Container Platform 5 openshift5/ose-monitoring-plugin-rhel9 Red Hat Openshift Data Foundation 4 odf4/mcg-core-rhel9, odf4/ocs-client-console-rhel9, rhceph-dev/odf4-mcg-core-rhel9, rhceph-dev/odf4-odf-console-rhel9, odf4/odf-multicluster-console-rhel9, rhceph-dev/odf4-ocs-client-console-rhel9, +1 more
    affected: workaround, no fix available
  • Red Hat Secrets Management Console for Red Hat OpenShift external-secrets-management/console-plugin-rhel9
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Cluster Observability Operator 1.5 cluster-observability-operator/monitoring-console-plugin-rhel9 1790854525, cluster-observability-operator/logging-console-plugin-pf4-rhel9 1790854525, cluster-observability-operator/monitoring-console-plugin-pf5-rhel9 1790854526, cluster-observability-operator/monitoring-console-plugin-pf6-rhel9 1790854528, cluster-observability-operator/distributed-tracing-console-plugin-rhel9 1793661918, cluster-observability-operator/distributed-tracing-console-plugin-rhel9 1793824908, +6 more
    fixed: vendor fix RHSA-2026:95591
  • Red Hat Ansible Automation Platform 2.1 ansible-automation-platform/automation-portal 1790254963
    fixed: vendor fix RHSA-2026:72712
  • Red Hat Ansible Automation Platform 2.2 ansible-automation-platform/automation-portal 1790256405, ansible-automation-platform/bootc-automation-portal-rhel9 1791865660
    fixed: vendor fix RHSA-2026:72722
  • Red Hat Developer Hub 1.9 rhdh/rhdh-hub-rhel9 1789554285
    fixed: vendor fix RHSA-2026:69248
show 18 more
  • Red Hat Developer Hub 1.10 rhdh/rhdh-hub-rhel9 1791311495, rhdh/red-hat-developer-hub-backstage-plugin-lightspeed-backend 1791242697, rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-backend 1791251282, rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-backend-module-loki 1791250355, rhdh/red-hat-developer-hub-backstage-plugin-scaffolder-backend-module-orchestrator 1791249640
    fixed: vendor fix RHSA-2026:76788
  • Red Hat Enterprise Linux AppStream (v. 8) nodejs 22.23.2-2.module+el8.10.0+24957+74108fbf, nodejs 24.21.0-1.module+el8.10.0+24927+ed3d907a, nodejs-libs 22.23.2-2.module+el8.10.0+24957+74108fbf, nodejs-libs 24.21.0-1.module+el8.10.0+24927+ed3d907a, npm 10.9.8-1.22.23.2.2.module+el8.10.0+24957+74108fbf, nodejs-nodemon 3.1.14-2.module+el8.10.0+24710+c2e9b41f, +8 more
    fixed: vendor fix RHSA-2026:75870
  • Red Hat Enterprise Linux AppStream (v. 9) nodejs 22.23.2-2.module+el9.8.0+24958+80b2ac6e, nodejs 24.21.0-1.module+el9.8.0+24924+cd677006, nodejs 24.22.1-5.module+el9.8.0+25292+33251f3b, nodejs-libs 22.23.2-2.module+el9.8.0+24958+80b2ac6e, nodejs-libs 24.21.0-1.module+el9.8.0+24924+cd677006, nodejs-libs 24.22.1-5.module+el9.8.0+25292+33251f3b, +13 more
    fixed: vendor fix RHSA-2026:76750
  • Red Hat Enterprise Linux AppStream (v. 10) nodejs 22.23.2-3.el10_2, nodejs22 22.23.2-3.el10_2, nodejs24 24.21.0-1.el10_2, nodejs-libs 22.23.2-3.el10_2, nodejs24-libs 24.21.0-1.el10_2, nodejs-full-i18n 22.23.2-3.el10_2, +3 more
    fixed: vendor fix RHSA-2026:75864
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) nodejs 22.23.2-2.el10_0, nodejs22 22.23.2-2.el10_0, nodejs-libs 22.23.2-2.el10_0, nodejs-full-i18n 22.23.2-2.el10_0, nodejs-npm 10.9.8-1.22.23.2.2.el10_0
    fixed: vendor fix RHSA-2026:84703
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) nodejs 22.23.2-2.module+el9.6.0+25055+19201b10, nodejs-libs 22.23.2-2.module+el9.6.0+25055+19201b10, npm 10.9.8-1.22.23.2.2.module+el9.6.0+25055+19201b10, nodejs-nodemon 3.1.14-2.module+el9.6.0+24789+4011c12f, nodejs-full-i18n 22.23.2-2.module+el9.6.0+25055+19201b10, nodejs-packaging 2021.06-4.module+el9.6.0+23473+45664c2d, +1 more
    fixed: vendor fix RHSA-2026:84589
  • Red Hat Hardened Images nodejs24 24.21.0-1.hum1, nodejs26 26.8.2-0.1.hum1, nodejs24-bin 24.21.0-1.hum1, grafana12.4 12.4.10-0.2.hum1, nodejs24-libs 24.21.0-1.hum1, nodejs26-bin 26.8.2-0.1.hum1, +7 more
    fixed: vendor fix RHSA-2026:66008
  • Red Hat OpenShift AI 2.25 rhoai/odh-workbench-codeserver-datascience-cpu-py312-rhel9 1791288400
    fixed: vendor fix RHSA-2026:87410
  • Red Hat OpenShift AI 3.4 rhoai/odh-dashboard-rhel9 1791861020, rhoai/odh-mod-arch-maas-rhel9 1791860708, rhoai/odh-mod-arch-automl-rhel9 1791861032, rhoai/odh-mod-arch-gen-ai-rhel9 1791861479, rhoai/odh-mod-arch-mlflow-rhel9 1791861383, rhoai/odh-mod-arch-autorag-rhel9 1791860994, +3 more
    fixed: vendor fix RHSA-2026:84734
  • Red Hat OpenShift AI 3.5 rhoai/odh-workbench-codeserver-datascience-cpu-py312-rhel9 1791825469
    fixed: vendor fix RHSA-2026:86891
  • Red Hat Openshift Data Foundation 4.19 odf4/odf-console-rhel9 1793126829
    fixed: vendor fix RHSA-2026:92650
  • Red Hat OpenShift Dev Spaces 3.31 devspaces/code-rhel9 1792599388, devspaces/openvsx-rhel9 1792494821, devspaces/dashboard-rhel9 1791945540, devspaces/pluginregistry-rhel9 1792495212
    fixed: vendor fix RHSA-2026:90321
  • Red Hat Trusted Artifact Signer 1.5 rhtas/rhtas-console-ui-rhel9 1793114810
    fixed: vendor fix RHSA-2026:95124
  • Red Hat Cluster Observability Operator 1.5 cluster-observability-operator/perses-rhel9 1790854501, cluster-observability-operator/perses-rhel9 1793661985, cluster-observability-operator/perses-rhel9 1793825744, cluster-observability-operator/thanos-rhel9 1790854526, cluster-observability-operator/thanos-rhel9 1793660568, cluster-observability-operator/thanos-rhel9 1793821585, +57 more
    not affected: vulnerable code not present
  • Red Hat Cryostat 4 cryostat/cryostat-openshift-console-plugin-rhel9
    not affected: component not present
  • Red Hat AMQ Broker 7 amq-broker-bin.zip 7.14.1.CR2, amq-broker-maven-repository.zip 7.14.1.CR3
    not affected: vulnerable code not in execute path
  • Red Hat Ansible Automation Platform 2 automation-platform-ui 2.6.13-1.el9ap
    not affected: component not present
  • Red Hat Developer Hub 1.9 rhdh/rhdh-rhel9-operator 1789552931, rhdh/rhdh-operator-bundle 1789558887 Red Hat Developer Hub 1.10 rhdh/rhdh-rhel9-operator 1791219676, rhdh/rhdh-operator-bundle 1791315788, rhdh/rhdh-must-gather-rhel9 1788278523, rhdh/rhdh-rag-content-rhel9 1791168570, rhdh/red-hat-developer-hub-backstage-plugin-lightspeed 1791242743, rhdh/red-hat-developer-hub-backstage-plugin-orchestrator 1791250003, +1 more Red Hat Enterprise Linux 10 grafana 12.4.3-2.el10 Red Hat Hardened Images rust 1.97.1-2.hum1, jaeger 2.20.0-0.8.hum1, prometheus3.13 3.13.2-0.2.hum1 Red Hat OpenShift AI 2.25 rhoai/odh-rhel9-operator 1792570619, rhoai/odh-vllm-cpu-rhel9 1792018436, rhoai/odh-dashboard-rhel9 1791853525, rhoai/odh-modelmesh-rhel9 1790881700, rhoai/odh-operator-bundle 1792571069, rhoai/odh-vllm-cuda-rhel9 1791358976, +65 more Red Hat OpenShift AI 3.4 rhoai/odh-cli-rhel9 1791509689, rhoai/rhai-cli-rhel9 1791509689, rhoai/odh-automl-rhel9 1791535789, rhoai/odh-mlflow-rhel9 1791865967, rhoai/odh-autorag-rhel9 1791557539, rhoai/odh-trainer-rhel9 1791869783, +91 more
    +2 more products
    Red Hat OpenShift AI 3.5 rhoai/odh-cli-rhel9 1791945905, rhoai/rhai-cli-rhel9 1791945905, rhoai/odh-automl-rhel9 1791916705, rhoai/odh-mlflow-rhel9 1791947857, rhoai/odh-autorag-rhel9 1791903266, rhoai/odh-trainer-rhel9 1791952138, +112 more Red Hat OpenShift Container Platform 4 wasmedge, wasmedge-rt
    not affected: vulnerable code not present

3 more not affected in the full advisory

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.39% chance of exploitation in the next 30 days, higher than 33% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm undici
>=6.7.0, <6.28.1
>=7.0.0, <7.29.1
>=8.0.0, <8.10.2
6.28.1
7.29.1
8.10.2

Affected products

  • undici undici

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.