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Medium, CVSS 5.9amended

Undici has Unbounded Memory Consumption in its DeduplicationHandler via Response Buffering that leads to DoS

CVE-2026-2581GHSA-phc3-fgpg-7m6h

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (undici 7.24.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm undici

    Affected
    >= 7.17.0, < 7.24.0
    Fixed in
    7.24.0

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
5.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
  • CVE-2026-2581: 0.59% estimated exploitation activity in the next 30 days; percentile 48.20 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-phc3-fgpg-7m6h

  2. Revision 1 · created ·

    Published from osv record GHSA-phc3-fgpg-7m6h

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-2581

Advisory: Undici has Unbounded Memory Consumption in its DeduplicationHandler via Response Buffering that leads to DoS
IDs: CVE-2026-2581, GHSA-phc3-fgpg-7m6h
Record: https://patchnext.com/advisories/cve-2026-2581 (revision 2, source checked 26 Oct 2026, 12:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: undici 7.24.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm undici: affected >= 7.17.0, < 7.24.0; fixed in 7.24.0

## Suggested inspection (read-only)
- `npm ls undici --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on undici.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-phc3-fgpg-7m6h (OSV record GHSA-phc3-fgpg-7m6h lists affected ranges: npm undici >=7.17.0 <7.24.0 (fixed))
- Verified: https://github.com/advisories/GHSA-phc3-fgpg-7m6h (GitHub-reviewed advisory GHSA-phc3-fgpg-7m6h lists affected ranges: npm undici >=7.17.0 <7.24.0)

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