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Fencer Intel
medium 6.5

CVE-2026-84933 json

undici vulnerable to cross-user cookie disclosure via Set-Cookie caching in shared caches

published 2mo ago modified last mo. also EUVD-2026-71518 , GHSA-2jfj-6hjv-fm6j

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 23%
public exploits
0
none known

Summary

undici's cache interceptor does not handle the Set-Cookie response header anywhere in its cache path, so it neither refuses to store nor strips that header. In shared cache mode, which is the default, an otherwise cacheable response that carries a Set-Cookie header, for example one marked with a public and max-age directive, is stored and then re-served to a later caller that matches the same cache key. As a result one caller's cookie is disclosed to a different caller, and an untrusted server can inject cookies into cached responses served to all subsequent callers. This violates the requirement that a shared cache must not store cookies. This affects undici versions from 7.0.0 up to 7.29.1 and from 8.0.0 up to 8.10.2. Users should upgrade to undici 7.29.1 or 8.10.2.

Patch / fix

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

debian advisories DEBIAN-CVE-2026-84933

  • grafana12.4 hummingbird 1 12.4.10-0.2.hum1
  • nodejs24 hummingbird 1 24.18.1-0.2.2.hum1
  • nodejs24-bin hummingbird 1 24.18.1-0.2.2.hum1
  • nodejs24-npm hummingbird 1 11.16.0-1.24.18.1.0.2.2.hum1
  • nodejs24-libs hummingbird 1 24.18.1-0.2.2.hum1
  • nodejs24-npm-bin hummingbird 1 24.18.1-0.2.2.hum1
  • nodejs24-full-i18n hummingbird 1 24.18.1-0.2.2.hum1
  • nodejs26 hummingbird 1 26.7.0-1.5.2.hum1

red hat advisories RHSA-2026:66008RHSA-2026:54438RHSA-2026:54389

  • pi-coding-agent openSUSE Leap 16.0 1.0.4-bp160.1.1
  • pi-coding-agent openSUSE Tumbleweed 0.87.1-1.1

opensuse advisories openSUSE-SU-2026:22111-1openSUSE-SU-2026:11884-1

Is CVE-2026-84933 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2026-84933 updated cvss 6.5

undici: undici: Cross-user cookie disclosure via Set-Cookie caching

  • 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 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 10 grafana 12.4.3-2.el10
    affected: workaround, no fix available “Fix deferred”
  • 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-core-bff-rhel9, rhoai/odh-dashboard-rhel9, rhoai/odh-mod-arch-maas-rhel9, rhoai/odh-mod-arch-automl-rhel9, rhoai/odh-mod-arch-gen-ai-rhel9, rhoai/odh-mod-arch-mlflow-rhel9, +6 more Red Hat OpenShift Container Platform 4 openshift4/ose-monitoring-plugin-rhel9 Red Hat OpenShift Dev Spaces devspaces/code-rhel9, devspaces/openvsx-rhel9, devspaces/dashboard-rhel9, devspaces/pluginregistry-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Trusted Artifact Signer rhtas/rhtas-console-ui-rhel9
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Hardened Images nodejs26 26.7.0-1.5.2.hum1, nodejs24 24.18.1-0.2.2.hum1, grafana12.4 12.4.10-0.2.hum1, nodejs26-bin 26.7.0-1.5.2.hum1, nodejs24-bin 24.18.1-0.2.2.hum1, nodejs26-libs 26.7.0-1.5.2.hum1, +7 more
    fixed: vendor fix RHSA-2026:66008
  • Red Hat Exploit Intelligence exploit-intelligence/vulnerability-analysis-rhel9 Red Hat AMQ Broker 7 amq-broker-bin.zip 7.14.1.CR2, amq-broker-maven-repository.zip 7.14.1.CR3 Red Hat Ansible Automation Platform 2 automation-platform-ui 2.6.13-1.el9ap Red Hat Enterprise Linux 8 npm, nodejs, nodejs-libs, nodejs-nodemon, ubi8/nodejs-24, nodejs-full-i18n, +3 more Red Hat Enterprise Linux 9 npm, nodejs, nodejs-libs, ubi9/nodejs-24, nodejs-full-i18n, ubi9/nodejs-24-minimal Red Hat Enterprise Linux 10 ubi10/nodejs-24, nodejs26 26.1.0-1.el10, ubi10/nodejs-24-minimal, nodejs22 22.23.2-1.el10_2, nodejs24 24.19.0-1.el10_2
    +6 more products
    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 (RHOAI) rhoai/odh-mlflow-rhel9 Red Hat OpenShift Container Platform 4 wasmedge, wasmedge-rt 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 Secrets Management Console for Red Hat OpenShift external-secrets-management/console-plugin-rhel9 Red Hat Self-service automation portal 2 ansible-automation-platform/automation-portal, ansible-automation-platform/bootc-automation-portal-rhel9
    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
no
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.30% chance of exploitation in the next 30 days, higher than 23% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N
NVD 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

Affected packages

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

Affected products

  • undici undici

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
  • CWE-524 Use of Cache Containing Sensitive Information

References

Sources

Fencer Intel 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.

The maintainers of nodejs/undici published their own advisory on GitHub. Reviewed sources take precedence over it.

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