CVE-2026-77078
HIGHDescription
multer is a middleware for handling multipart/form-data in Node.js. A small multipart request containing two specially crafted text field names can cause an uncaught RangeError (Invalid array length) that terminates the Node.js process. The first field uses a very large numeric array index to allocate a maximum-length sparse array, and a second field then pushes past that length, which throws inside the append-field dependency and is not caught by multer. All versions before 2.3.0 are affected, and the issue is a remotely triggerable denial of service. The issue is fixed in multer 2.3.0. Upgrade to multer 2.3.0 to remediate.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 22% of all known CVEs.
References
Related Vulnerabilities
Other CWE-248 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2025-59538 | High | 7.5 | 8.9% | - | Fix |
| CVE-2025-53366 | High | 8.7 | 7.3% | - | - |
| CVE-2021-37714 | High | 7.5 | 6.9% | - | Fix |
| CVE-2018-11466 | Critical | 9.8 | 4.0% | - | - |
| CVE-2025-59465 | High | 7.5 | 3.8% | - | Fix |
| CVE-2018-7852 | High | 7.5 | 3.6% | - | - |
Common questions
How do I fix CVE-2026-77078?
Upgrade multer to 2.3.0 or later.
Is CVE-2026-77078 being actively exploited?
Not that we know of. CVE-2026-77078 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.29% is the estimated probability that it will be exploited in the next 30 days. That is higher than 22% of all scored CVEs.
How severe is CVE-2026-77078?
CVE-2026-77078 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-77078 affect?
Published advisories record a fix for multer (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-02.