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OpenAdvisories
Medium · 5.9 CVE-2026-85024 EUVD-2026-71603GHSA-3wwx-pv8p-q78v

undici vulnerable to Denial of Service via unhandled error in WebSocket permessage-deflate decompression

Published Sep 4, 2026 · Updated Sep 4, 2026 · Assigned by openjs

Description

undici bundles a WebSocket client whose permessage-deflate size-limit cleanup removes all listeners from the internal zlib inflate stream, including its error listener, while that stream can still emit. When a remote peer sends a compressed payload that crosses the built-in 128 MiB decompressed-payload limit and then contains a malformed DEFLATE byte, the inflate stream emits a data error with no listener attached, which Node.js treats as a fatal unhandled error and terminates the entire process. Exploitation is remote and unauthenticated, requires no application mistake, and is asymmetric, since roughly 130 KB on the wire expands past the limit and crashes the process, and reconnecting can repeat the crash. This affects undici versions from 6.25.0 up to 6.28.1, from 7.28.0 up to 7.29.1, and from 8.1.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.

Affected products

VendorProductAffectedFixed
undici undici 6.25.0 – < 6.28.1, 7.28.0 – < 7.29.1, 8.1.0 – < 8.10.2 6.28.1

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 node-undici 8.10.2+dfsg+~cs3.2.2-1 —
Debian 13 node-undici No fix yet —
Debian 12 node-undici No fix yet —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 node-undici No fix yet —
Ubuntu 26.04 LTS node-undici No fix yet —
Ubuntu 24.04 LTS node-undici No fix yet —
ReleasePackageFixed inAdvisory
Red Hat Hardened Images 1 grafana12.4 12.4.9-0.6.hum1 RHSA-2026:63782
Red Hat Hardened Images 1 nodejs24 +5 1:24.21.0-1.hum1 RHSA-2026:71017
Red Hat Hardened Images 1 nodejs24-npm +1 2:11.19.0-1.24.21.0.1.hum1 RHSA-2026:71017
Red Hat Hardened Images 1 nodejs26 +6 1:26.8.2-0.1.hum1 RHSA-2026:66605
Red Hat Hardened Images 1 nodejs26-npm 1:11.19.1-1.26.8.2.0.1.hum1 RHSA-2026:66605
ReleasePackageFixed inAdvisory
openSUSE Leap 16.0 pi-coding-agent 1.0.4-bp160.1.1 openSUSE-SU-2026:22111-1

Amazon Linux

ReleasePackageFixed inAdvisory
Amazon Linux 2023 nodejs22 +4 1:22.23.2-1.amzn2023.0.3 ALAS2023-2026-3123
Amazon Linux 2023 nodejs22-npm 1:10.9.8-1.22.23.2.1.amzn2023.0.3 ALAS2023-2026-3123
Amazon Linux 2023 nodejs24 +4 1:24.21.0-1.amzn2023.0.1 ALAS2023-2026-3107
Amazon Linux 2023 nodejs24-npm 1:11.19.0-1.24.21.0.1.amzn2023.0.1 ALAS2023-2026-3107
Amazon Linux 2023 v8-12.4-devel 3:12.4.254.21-1.22.23.2.1.amzn2023.0.3 ALAS2023-2026-3123
Amazon Linux 2023 v8-13.6-devel 3:13.6.233.17-1.24.21.0.1.amzn2023.0.1 ALAS2023-2026-3107

Wolfi

ReleasePackageFixed inAdvisory
Wolfi rolling code-server 4.139.1-r2 —
Wolfi rolling lerna 10.0.1-r11 —
Wolfi rolling prism 5.16.0-r14 —
Wolfi rolling pulumi-language-nodejs 3.265.0-r3 —
Wolfi rolling renovate 44.118.2-r0 —
Wolfi rolling vitess-24 24.0.3-r9 —

Affected packages

EcosystemPackageAffectedFixedRecord
npm undici >= 6.25.0, < 6.28.1 6.28.1 GHSA-3wwx-pv8p-q78v
npm undici >= 7.28.0, < 7.29.1 7.29.1 GHSA-3wwx-pv8p-q78v
npm undici >= 8.1.0, < 8.10.2 8.10.2 GHSA-3wwx-pv8p-q78v

Advisories 7

References