7.5

CVE-2026-77078: expressjs multer Uncaught Exception

CVSS: 7.5v3.1HighAnalyzed
AliasesGHSA-wc9g-mqfw-jrwm
Published 28-08-2026Last modified 31-08-2026
Open JSON

Vulnerability summary

CVE-2026-77078 is a high (CVSS 7.5) Uncaught Exception vulnerability in expressjs multer. EPSS estimates a 0.49% chance of exploitation in the next 30 days, higher than 40.7% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.49%
0%100%
Low · +0.20 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 28-08-2026
    PublishedVulnerability first disclosed.
  2. 31-08-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.49%

Chance of exploitation in the next 30 days

Percentile

41%

Versus all other CVEs

30-day change

+0.20 pp

From 0.29% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.49%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Expressjs1 product
Multer1 product
Npm1 product
  • multer< 2.3.0

3 vendors · 3 products

References

6 links