CVE-2026-5079
Description
A flaw was found in Multer. A remote attacker can exploit this vulnerability by sending a single HTTP request with crafted multipart form data containing deeply nested field names. This can force the allocation of deeply nested object structures, consuming excessive CPU and memory resources. The vulnerability ultimately leads to a Denial of Service (DoS) for the affected system.
Statement
This is an Important denial of service vulnerability in Multer, a Node.js middleware for handling multipart/form-data. An attacker can exploit this flaw by sending a crafted HTTP request with deeply nested field names, leading to excessive resource consumption and service unavailability. This is particularly relevant for Red Hat products that expose Multer-based services to untrusted network input.
Mitigation
To reduce the impact of this denial of service vulnerability, configure the `limits.fields` option within your `multer` instance to a reasonable maximum value. This action restricts the number of fields processed from multipart form data, thereby limiting the resources an attacker can consume. This partial mitigation requires an application restart to take effect and does not fully prevent the vulnerability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (Other)
If parsed, recursive entity references allow the attacker to expand data exponentially, quickly consuming all system resources.
Frequently Asked Questions
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