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Fencer Vulns
high 7.5

CVE-2026-87018 json

undici vulnerable to Denial of Service via TLS 1.2 certificate-changing renegotiation

published 2026-10-15 24 d ago modified 2026-10-27 12 d ago also GHSA-qrxm-fqhp-jwvm , EUVD-2026-102318

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 8%
public exploits
0
none known

Summary

undici is an HTTP client library for Node.js. In versions 4.2.1 through 6.29.0, 7.0.0 through 7.30.0, and 8.0.0 through 8.12.1, the client process crashes when a TLS 1.2 server renegotiates after the connection is established and presents a different, CA-trusted certificate whose hostname does not match the requested host. Node.js re-runs hostname verification on the renegotiated handshake and destroys the socket with a certificate-altname error, but undici's established-socket error handler asserted that this error code could never occur, so the peer-controlled error became an uncaught assertion that terminates the Node.js process, affecting both the HTTP/1.1 and HTTP/2 paths. A malicious or compromised HTTPS endpoint reached through undici or the global fetch() can crash the client with a single server-initiated renegotiation, taking down all in-flight requests and background work in the process, and exploitation needs no CA compromise because the attacker controls the endpoint and can present two ordinary valid certificates. Only TLS 1.2 is affected, since TLS 1.3 does not support renegotiation. The issue is fixed in undici 6.29.1, 7.30.1, and 8.12.2, and users should upgrade to one of those versions or later. As a workaround, restrict outbound connections to TLS 1.3 so renegotiation cannot occur, when the target endpoints support it.

Patch / fix

  • npm undici 6.29.1, 7.30.1, 8.12.2
  • undici undici 6.29.1, 7.30.1, 8.12.2
  • node-undici Debian 14 8.12.2+dfsg+~cs3.2.3-1

debian advisories DEBIAN-CVE-2026-87018

  • nodejs24 hummingbird 1 24.21.0-1.5.hum1
  • nodejs24-bin hummingbird 1 24.21.0-1.5.hum1
  • nodejs24-npm hummingbird 1 11.19.0-1.24.21.0.1.5.hum1
  • nodejs24-libs hummingbird 1 24.21.0-1.5.hum1
  • nodejs24-npm-bin hummingbird 1 24.21.0-1.5.hum1
  • nodejs24-full-i18n hummingbird 1 24.21.0-1.5.hum1
  • nodejs26 hummingbird 1 26.11.1-0.4.hum1
  • nodejs26-bin hummingbird 1 26.11.1-0.4.hum1

red hat advisories RHSA-2026:84706RHSA-2026:84657

  • pi-coding-agent openSUSE Tumbleweed 1.5.0-1.1

opensuse advisories openSUSE-SU-2026:12421-1

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-2026-87018 updated cvss 7.5

undici: undici: Denial of Service via TLS renegotiation with mismatched certificate

  • Red Hat Exploit Intelligence exploit-intelligence/vulnerability-analysis-rhel9 Red Hat AMQ Broker 7 amq-broker-maven-repository.zip 7.14.1.CR3 Red Hat Build of Podman Desktop rh-podman-desktop a4ea1f988eb28bc86ab3516bba3a4973b252a17e Red Hat Developer Hub 1 rhdh/rhdh-hub-rhel9, rhdh/red-hat-developer-hub-backstage-plugin-lightspeed-backend, rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-backend, rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-backend-module-loki, rhdh/red-hat-developer-hub-backstage-plugin-scaffolder-backend-module-orchestrator Red Hat Enterprise Linux 8 npm, nodejs, nodejs-libs, ubi8/s2i-base, nodejs-nodemon, ubi8/nodejs-24, +4 more Red Hat Enterprise Linux 9 npm, nodejs, nodejs-libs, ubi9/nodejs-24, nodejs-full-i18n, ubi9/nodejs-24-minimal
    +1 more products
    Red Hat Enterprise Linux 10 nodejs26
    affected: no fix available
  • Red Hat Hardened Images nodejs25 25.9.0-1.7.hum1
    affected: 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, rhoai/odh-workbench-codeserver-datascience-cpu-py312-rhel9 Red Hat OpenShift Container Platform 4 wasmedge, wasmedge-rt, 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/odf-console-rhel9, odf4/ocs-client-console-rhel9, odf4/odf-multicluster-console-rhel9 Red Hat OpenShift Dev Spaces devspaces/code-rhel9, devspaces/openvsx-rhel9, devspaces/dashboard-rhel9, devspaces/pluginregistry-rhel9
    affected: no fix available
  • Red Hat Secrets Management Console for Red Hat OpenShift external-secrets-management/console-plugin-rhel9
    affected: no fix planned “Will not fix”
  • Red Hat Self-service automation portal 2 ansible-automation-platform/automation-portal, ansible-automation-platform/bootc-automation-portal-rhel9
    affected: no fix available
  • Red Hat Cluster Observability Operator 1.5 cluster-observability-operator/monitoring-console-plugin-rhel9 1793663585, cluster-observability-operator/monitoring-console-plugin-rhel9 1793827684, cluster-observability-operator/logging-console-plugin-pf4-rhel9 1793660952, cluster-observability-operator/logging-console-plugin-pf4-rhel9 1793824934, cluster-observability-operator/monitoring-console-plugin-pf5-rhel9 1793662327, cluster-observability-operator/monitoring-console-plugin-pf5-rhel9 1793827768, +10 more
    fixed: vendor fix RHSA-2026:95591
  • Red Hat Enterprise Linux AppStream (v. 10) nodejs 22.23.4-1.el10_2, nodejs22 22.23.4-1.el10_2, nodejs24 24.22.1-3.el10_2, nodejs-libs 22.23.4-1.el10_2, nodejs24-libs 24.22.1-3.el10_2, nodejs-full-i18n 22.23.4-1.el10_2, +3 more
    fixed: vendor fix RHSA-2026:96094
  • Red Hat Hardened Images nodejs24 24.21.0-1.5.hum1, nodejs26 26.11.1-0.4.hum1, nodejs26 26.11.1-0.5.hum1, nodejs26 26.12.1-0.1.hum1, nodejs24-bin 24.21.0-1.5.hum1, nodejs26-bin 26.11.1-0.4.hum1, +18 more
    fixed: vendor fix RHSA-2026:84706
show 5 more
  • Red Hat OpenShift AI 3.4 rhoai/odh-dashboard-rhel9 1793001801, rhoai/odh-mod-arch-maas-rhel9 1793001859, rhoai/odh-mod-arch-automl-rhel9 1793001841, rhoai/odh-mod-arch-gen-ai-rhel9 1793001896, rhoai/odh-mod-arch-mlflow-rhel9 1793001851, rhoai/odh-mod-arch-autorag-rhel9 1793001850, +2 more
    fixed: vendor fix RHSA-2026:92510
  • 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 1793661985, cluster-observability-operator/perses-rhel9 1793825744, cluster-observability-operator/thanos-rhel9 1793660568, cluster-observability-operator/thanos-rhel9 1793821585, cluster-observability-operator/korrel8r-rhel9 1793661297, cluster-observability-operator/korrel8r-rhel9 1793822079, +28 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.CR3 Red Hat Ansible Automation Platform 2 automation-platform-ui 2.6.15-1.el9ap Red Hat Enterprise Linux 10 grafana 12.4.3-2.el10 Red Hat Hardened Images grafana12.4 12.4.12-0.4.hum1 Red Hat OpenShift AI 3.4 rhoai/odh-cli-rhel9 1792722177, rhoai/rhai-cli-rhel9 1792722177, rhoai/odh-automl-rhel9 1792697253, rhoai/odh-mlflow-rhel9 1793002327, rhoai/odh-autorag-rhel9 1793265800, rhoai/odh-trainer-rhel9 1792817113, +92 more Red Hat Trusted Artifact Signer 1.5 rhtas/rhtas-console-rhel9 1793108442
    not affected: vulnerable code not present

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
23 d ago

Exploit prediction

0.19% chance of exploitation in the next 30 days, higher than 8% 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
>=4.2.1, <6.29.1
>=7.0.0, <7.30.1
>=8.0.0, <8.12.2
6.29.1
7.30.1
8.12.2

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.