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Fencer Vulns
high 7.5

CVE-2026-77037 json

multer vulnerable to Denial of Service via file descriptor leak on aborted uploads

published 2026-08-28 2 mo ago modified 2026-09-08 2 mo ago also GHSA-qfvm-cv95-jqjf , EUVD-2026-67928

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 39%
public exploits
0
none known

Summary

multer is a middleware for handling multipart/form-data in Node.js. In version 2.2.0, when a disk-backed upload is aborted or truncated before the write stream finishes, multer's disk storage engine removes the visible file but does not close the underlying write file descriptor, leaving a deleted but still open descriptor. A remote attacker able to reach an upload route using the built-in disk storage can send repeated aborted or malformed multipart uploads, each one leaking a file descriptor and retaining disk blocks until the process exits, which can exhaust resources and cause a denial of service. The issue is fixed in multer 2.3.0, which closes the destination write stream on abnormal source termination and defers cleanup until the stream has closed. Upgrade to multer 2.3.0 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-2026-77037

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-2026-77037 updated cvss 7.5

multer: Multer: Denial of Service via file descriptor leak on aborted uploads

  • Red Hat Logging Subsystem for Red Hat OpenShift openshift-logging/vector-rhel9
    affected: workaround, no fix planned “Upgrade to multer 2.3.0 or later, which properly closes the destination write stream on abnormal source termination and defers cleanup until the stream has closed.”
  • Red Hat Developer Hub 1 rhdh/red-hat-developer-hub-backstage-plugin-lightspeed-backend 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 “Upgrade to multer 2.3.0 or later, which properly closes the destination write stream on abnormal source termination and defers cleanup until the stream has closed.”
  • Red Hat Ansible Automation Platform 2.2 ansible-automation-platform/automation-portal 1792523640, ansible-automation-platform/bootc-automation-portal-rhel9 1791865660
    fixed: vendor fix “Upgrade to multer 2.3.0 or later, which properly closes the destination write stream on abnormal source termination and defers cleanup until the stream has closed.” RHSA-2026:86675
  • Red Hat Developer Hub 1.10 rhdh/rhdh-hub-rhel9 1791311495, rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-backend 1791251282
    fixed: vendor fix “Upgrade to multer 2.3.0 or later, which properly closes the destination write stream on abnormal source termination and defers cleanup until the stream has closed.” 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, +4 more
    not affected: vulnerable code not present
  • Red Hat Enterprise Linux 7 firefox Red Hat Enterprise Linux 8 thunderbird Red Hat Enterprise Linux 9 firefox, firefox-x11, thunderbird Red Hat Enterprise Linux 10 firefox, thunderbird 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
2 mo ago

Exploit prediction

0.46% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-08).

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
>=2.2.0, <2.3.0
2.3.0

Affected products

  • multer multer

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-459 Incomplete Cleanup

References

Sources

Fencer Vulns 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.