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CVE-2026-77037— multer vulnerable to Denial of Service via file descriptor leak on aborted uploads

Quick assessment

Affected
multer multer
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

expressjs Multer是expressjs组织开源的一个用于Node.js中间件。 expressjs Multer 2.2.0版本存在资源管理错误漏洞，该漏洞源于磁盘备份上传在写流完成前被中止或截断时，磁盘存储引擎未关闭底层写文件描述符，导致远程攻击者通过发送重复的中止或畸形multipart上传，泄漏文件描述符并保留磁盘块，造成资源耗尽和拒绝服务。

CVSS 7.5 · High EPSS 0.35% · P27

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 2

VendorProduct Version RangeStatus
multer multer 2.2.0< 2.3.0 affected
2.3.0 unaffected
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I. Basic Information for CVE-2026-77037

Vulnerability Information
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Vulnerability Title
multer vulnerable to Denial of Service via file descriptor leak on aborted uploads
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5
Vulnerability Title
expressjs Multer 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
expressjs Multer是expressjs组织开源的一个用于Node.js中间件。 expressjs Multer 2.2.0版本存在资源管理错误漏洞，该漏洞源于磁盘备份上传在写流完成前被中止或截断时，磁盘存储引擎未关闭底层写文件描述符，导致远程攻击者通过发送重复的中止或畸形multipart上传，泄漏文件描述符并保留磁盘块，造成资源耗尽和拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
multer multer 2.2.0 ~ 2.3.0 -

II. Public POCs for CVE-2026-77037

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III. Intelligence Information for CVE-2026-77037

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Vendor Advisories for CVE-2026-77037 (1)

Same Patch Batch · multer · 2026-08-28 · 4 CVEs total

CVE-2026-77078 7.5 HIGH multer vulnerable to Denial of Service via crafted multipart field names
CVE-2026-82333 7.5 HIGH multer vulnerable to Denial of Service via oversized array index in field names
CVE-2026-77063 3.7 LOW multer vulnerable to file size limit bypass via async fileFilter race condition

IV. Related Vulnerabilities

Same product: multer
Same vendor: multer
Same weakness: CWE-400

V. Comments for CVE-2026-77037

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