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MEDIUM severity

Undici has Unbounded Memory Consumption in its DeduplicationHandler via Response Buffering that leads to DoSGHSA-phc3-fgpg-7m6h

MEDIUM

GHSA-phc3-fgpg-7m6h is a medium-severity (CVSS 5.9) CWE-770 vulnerability in undici. A fix is available for undici — see the affected versions and patch details below.

Also known asCVE-2026-2581
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-phc3-fgpg-7m6h.

EPSS Exploitation Probability

via FIRST.org ↗
0.6%probability of exploitation in next 30 days
Lower Risk-0.12%
Lower risk than most CVEs48th percentile — riskier than 48% of all scored CVEsHighest risk
0.00%0.40%0.81%1.21%0.0%0.6%May 26Aug 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

9Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream
undicinpm
316.1Mdownloads / week

Description

Impact

This is an uncontrolled resource consumption vulnerability (CWE-400) that can lead to Denial of Service (DoS).

In vulnerable Undici versions, when interceptors.deduplicate() is enabled, response data for deduplicated requests could be accumulated in memory for downstream handlers. An attacker-controlled or untrusted upstream endpoint can exploit this with large/chunked responses and concurrent identical requests, causing high memory usage and potential OOM process termination.

Impacted users are applications that use Undici’s deduplication interceptor against endpoints that may produce large or long-lived response bodies.

Patches

The issue has been patched by changing deduplication behavior to stream response chunks to downstream handlers as they arrive (instead of full-body accumulation), and by preventing late deduplication when body streaming has already started.

Users should upgrade to the first official Undici (and Node.js, where applicable) releases that include this patch.

Workarounds

If upgrading immediately is not possible:

  • Disable interceptors.deduplicate() for affected clients/routes.
  • Use skipHeaderNames with a marker header to force high-risk requests to bypass deduplication.
  • Avoid concurrent identical requests to untrusted endpoints that may return very large/chunked bodies.
  • Apply upstream/proxy response-size and timeout limits.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmundici≥ 7.17.0&&< 7.24.07.24.0npm install undici@7.24.0

Affected Products

1 product · 1 configurations
Application
undicinodejs
≥ 7.17.0 && < 7.24.0
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for undici, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update undici to 7.24.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-phc3-fgpg-7m6h is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate
Workaround published by Red Hat
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Source: Red Hat security advisory for GHSA-phc3-fgpg-7m6h (CC BY 4.0)
ProductFixed inAdvisory
Red Hat Enterprise Linux 10nodejs24-1:24.14.1-2.el10_1RHSA-2026:7675
Red Hat Enterprise Linux 8nodejs:24-8100020260408131901.6d880403RHSA-2026:7670
Red Hat Enterprise Linux 9nodejs:24-9070020260402152654.rhel9RHSA-2026:7350

Frequently Asked Questions

## Impact This is an uncontrolled resource consumption vulnerability (CWE-400) that can lead to Denial of Service (DoS). In vulnerable Undici versions, when `interceptors.deduplicate()` is enabled, response data for deduplicated requests could be accumulated in memory for downstream handlers. An attacker-controlled or untrusted upstream endpoint can exploit this with large/chunked responses and concurrent identical requests, causing high memory usage and potential OOM process termination. Impacted users are applications that use Undici’s deduplication interceptor against endpoints that may p
O3 Security · Impact-Aware SCA

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