#VU111105 Memory leak in multer - CVE-2025-47935

Vulnerability identifier: #VU111105

Vulnerability risk: High

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2025-47935

CWE-ID: CWE-401

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
multer
Other software / Other software solutions

Vendor: Express.js

Description
The vulnerability allows a remote attacker to perform DoS attack on the target system.

The vulnerability exists due to improper stream handling. When the HTTP request stream emits an error, the internal `busboy` stream is not closed, violating Node.js stream safety guidance. A remote attacker can force the application to leak memory and perform denial of service attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

multer: 1.0.0 - 1.4.5.2

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External links
https://github.com/expressjs/multer/commit/2c8505f207d923dd8de13a9f93a4563e59933665
https://github.com/expressjs/multer/pull/1120
https://github.com/expressjs/multer/security/advisories/GHSA-44fp-w29j-9vj5

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.