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Fencer Intel
high 7.5

CVE-2026-82333 json

multer vulnerable to Denial of Service via oversized array index in field names

published 2mo ago modified 2mo ago also EUVD-2026-67932 , GHSA-535w-7cp7-47q4

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits
0
none known

Summary

multer is a middleware for handling multipart/form-data in Node.js. A small multipart request with two specially crafted text field names can make multer's field parser synchronously iterate a maximum-length sparse array, blocking the event loop so the process cannot handle other requests. A large numeric array index in the first field allocates a maximum-length sparse array, and a second field with a non-numeric key then triggers a full-length iteration inside the append-field dependency. All versions before 2.3.0 are affected, and this is a remotely triggerable denial of service. multer 2.3.0 adds an opt-in fieldArrayIndexLimit option that rejects oversized array indexes. Upgrade to multer 2.3.0 and set limits.fieldArrayIndexLimit to the largest array index your application needs to remediate.

Patch / fix

  • npm multer 2.3.0
  • multer multer 2.3.0
  • node-multer Debian 14 2.4.0+~cs3.2.0-1

debian advisories DEBIAN-CVE-2026-82333

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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-2026-82333 updated cvss 7.5

multer: Multer: Denial of Service via oversized array index in field names

  • Red Hat Logging Subsystem for Red Hat OpenShift openshift-logging/vector-rhel9
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux 9 fdo-init, fdo-client, fdo-admin-cli, fdo-owner-cli, fdo-rendezvous-server, fdo-manufacturing-server, +1 more Red Hat Trusted Profile Analyzer rhtpa/rhtpa-trustification-service-rhel9
    affected: workaround, no fix available
  • Red Hat Ansible Automation Platform 2.2 ansible-automation-platform/automation-portal 1792523640, ansible-automation-platform/bootc-automation-portal-rhel9 1791865660
    fixed: vendor fix RHSA-2026:86675
  • Red Hat Developer Hub 1.10 rhdh/rhdh-hub-rhel9 1791311495, rhdh/red-hat-developer-hub-backstage-plugin-lightspeed-backend 1791242697, rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-backend 1791251282
    fixed: vendor fix RHSA-2026:76788
  • Red Hat 3scale API Management Platform 2 3scale-amp2/system-rhel8
    not affected: component not present
  • Red Hat Developer Hub 1.10 rhdh/rhdh-rhel9-operator 1791219676, rhdh/rhdh-operator-bundle 1791315788, rhdh/rhdh-must-gather-rhel9 1788278523, rhdh/rhdh-rag-content-rhel9 1791168570, rhdh/red-hat-developer-hub-backstage-plugin-lightspeed 1791242743, rhdh/red-hat-developer-hub-backstage-plugin-orchestrator 1791250003, +3 more
    not affected: vulnerable code not present
  • Red Hat Enterprise Linux 7 firefox Red Hat Enterprise Linux 8 thunderbird
    not affected: vulnerable code not in execute path
  • Red Hat Enterprise Linux 9 firefox, firefox-x11, thunderbird
    not affected: component not present
show 2 more
  • Red Hat Enterprise Linux 10 firefox, thunderbird
    not affected: vulnerable code not in execute path
  • Red Hat Hardened Images rust, netavark, openshell
    not affected: component 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
yes
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 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 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm multer
<2.3.0
2.3.0

Affected products

  • multer multer

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

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 expressjs/multer published their own advisory on GitHub. Reviewed sources take precedence over it.