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CVE-2026-77078— multer vulnerable to Denial of Service via crafted multipart field names

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.

multer 是 Node.js 中用于处理 multipart/form-data 的中间件。一个包含两个精心构造的文本字段名称的小型 multipart 请求，可以引发未捕获的 RangeError（无效的数组长度），从而导致 Node.js 进程终止。第一个字段使用一个非常大的数值型数组索引来分配一个最大长度的稀疏数组，第二个字段随后向该数组追加数据，超出了其长度，在 append-field 依赖项中抛出异常，且该异常未被 multer 捕获。所有 2.3.0 之前的版本均受此漏洞影响，且该问题可被远程触发

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1029 · Scheduled Transfer
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I. Basic Information for CVE-2026-77078

Vulnerability Information
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Vulnerability Title
multer vulnerable to Denial of Service via crafted multipart field names
Source: CVE Program / CVE List V5
Vulnerability 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.
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
未捕获的异常
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
multer multer 0 ~ 2.3.0 -

II. Public POCs for CVE-2026-77078

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III. Intelligence Information for CVE-2026-77078

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Vendor Advisories for CVE-2026-77078 (1)

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

CVE-2026-77037 7.5 HIGH multer vulnerable to Denial of Service via file descriptor leak on aborted uploads
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-248

V. Comments for CVE-2026-77078

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