CVE-2026-77037
multer vulnerable to Denial of Service via file descriptor leak on aborted uploads
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.
INFO
Published Date :
Aug. 28, 2026, 10:16 p.m.
Last Modified :
Sept. 2, 2026, 2:47 p.m.
Remotely Exploit :
No
Source :
ce714d77-add3-4f53-aff5-83d477b104bb
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | ce714d77-add3-4f53-aff5-83d477b104bb | ||||
| CVSS 3.1 | HIGH | MITRE-CVE |
Solution
- Upgrade Multer to version 2.3.0.
- Ensure file descriptors are properly closed.
- Monitor resource utilization.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-77037.
| URL | Resource |
|---|---|
| https://cna.openjsf.org/security-advisories.html | Vendor Advisory |
| https://github.com/expressjs/multer/security/advisories/GHSA-qfvm-cv95-jqjf | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-77037 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-77037
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-77037 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-77037 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Sep. 02, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:expressjs:multer:2.2.0:*:*:*:*:node.js:*:* Added Reference Type openjs: https://cna.openjsf.org/security-advisories.html Types: Vendor Advisory Added Reference Type openjs: https://github.com/expressjs/multer/security/advisories/GHSA-qfvm-cv95-jqjf Types: Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 31, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-77037', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-31T18:41:18.978508Z'} -
New CVE Received by ce714d77-add3-4f53-aff5-83d477b104bb
Aug. 28, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-400 Added CWE CWE-459 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/77xxx/CVE-2026-77037.json">CVE-2026-77037</a> Added Reference https://cna.openjsf.org/security-advisories.html Added Reference https://github.com/expressjs/multer/security/advisories/GHSA-qfvm-cv95-jqjf