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Fencer Intel
medium 5.9

CVE-2026-109924 json

undici vulnerable to Denial of Service via unbounded memory in the EventSource parser

published 25d ago modified 17d ago also GHSA-4qv8-2p9j-2685 , EUVD-2026-102249

cvss
5.9
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 25%
public exploits
0
none known

Summary

undici is an HTTP client library for Node.js. In versions 6.5.0 through 6.29.0, 7.0.0 through 7.30.0, and 8.0.0 through 8.12.1, its EventSource client can be driven to exhaust process memory by a malicious or compromised Server-Sent Events peer. By sending millions of tiny completed data fields with no blank event separator, or a single unfinished line split across many chunks, the parser retains a growing amount of per-field and per-chunk state that the byte-based maxEventSize and maxResponseSize limits do not bound, and because maxResponseSize is enforced on the compressed body before decompression, a small compressed response can expand into enough retained memory to terminate the process. An application only needs to maintain an EventSource connection to an untrusted peer, which controls only the response, and availability is the only impact. The issue is fixed in undici 6.29.1, 7.30.1, and 8.12.2, which bound the retained parser state independently of the byte limits, and users should upgrade to one of those versions or later. There is no workaround.

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-2026-109924

  • 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

Is CVE-2026-109924 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-2026-109924 updated cvss 5.9

undici: undici: Denial of Service via memory exhaustion in EventSource client

  • Red Hat Cryostat 4 cryostat/cryostat-openshift-console-plugin-rhel9
    affected: no fix available “Fix deferred”
  • Red Hat Exploit Intelligence exploit-intelligence/vulnerability-analysis-rhel9
    affected: no fix planned “Out of support scope”
  • Red Hat AMQ Broker 7 amq-broker-bin.zip 7.14.1.CR3, amq-broker-maven-repository.zip 7.14.1.CR3 Red Hat Ansible Automation Platform 2 automation-platform-ui 2.6.15-1.el9ap Red Hat Build of Podman Desktop rh-podman-desktop a4ea1f988eb28bc86ab3516bba3a4973b252a17e
    affected: no fix available “Fix deferred”
  • 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
    affected: no fix available
  • 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 Red Hat Enterprise Linux 10 ubi10/nodejs-24, grafana 12.4.3-2.el10, nodejs26 26.1.0-1.el10, ubi10/nodejs-24-minimal, nodejs22 22.23.2-3.el10_2, nodejs24 24.21.0-1.el10_2
    affected: no fix available “Fix deferred”
  • 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-rhel9, rhoai/odh-mod-arch-maas-rhel9, rhoai/odh-mod-arch-automl-rhel9, rhoai/odh-mod-arch-gen-ai-rhel9, +7 more 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
    affected: no fix available “Fix deferred”
  • Red Hat OpenShift Dev Spaces devspaces/code-rhel9, devspaces/openvsx-rhel9, devspaces/dashboard-rhel9, devspaces/pluginregistry-rhel9
    affected: no fix available
show 5 more
  • Red Hat Secrets Management Console for Red Hat OpenShift external-secrets-management/console-plugin-rhel9
    affected: no fix planned “Out of support scope”
  • Red Hat Self-service automation portal 2 ansible-automation-platform/automation-portal, ansible-automation-platform/bootc-automation-portal-rhel9
    affected: no fix available “Fix deferred”
  • Red Hat Hardened Images nodejs24 24.21.0-1.5.hum1, nodejs26 26.11.1-0.4.hum1, nodejs26 26.12.1-0.1.hum1, nodejs24-bin 24.21.0-1.5.hum1, nodejs26-bin 26.11.1-0.4.hum1, nodejs26-bin 26.12.1-0.1.hum1, +12 more
    fixed: vendor fix RHSA-2026:84706
  • Red Hat Trusted Artifact Signer 1.5 rhtas/rhtas-console-ui-rhel9 1793114810
    fixed: vendor fix RHSA-2026:95124
  • Red Hat Hardened Images grafana12.4 12.4.12-0.4.hum1 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
no
Technical impact
partial
Assessed
24d ago

Exploit prediction

0.32% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 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 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm undici
>=6.5.0, <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
  • CWE-770 Allocation of Resources Without Limits or Throttling

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.