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Multer vulnerable to Denial of Service via memory leaks from unclosed streams

High severity GitHub Reviewed Published May 19, 2025 in expressjs/multer • Updated May 19, 2025

Package

npm multer (npm)

Affected versions

< 2.0.0

Patched versions

2.0.0

Description

Impact

Multer <2.0.0 is vulnerable to a resource exhaustion and memory leak issue 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.

This leads to unclosed streams accumulating over time, consuming memory and file descriptors. Under sustained or repeated failure conditions, this can result in denial of service, requiring manual server restarts to recover. All users of Multer handling file uploads are potentially impacted.

Patches

Users should upgrade to 2.0.0

Workarounds

None

References

References

@ctcpip ctcpip published to expressjs/multer May 19, 2025
Published by the National Vulnerability Database May 19, 2025
Published to the GitHub Advisory Database May 19, 2025
Reviewed May 19, 2025
Last updated May 19, 2025

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(10th percentile)

Weaknesses

CVE ID

CVE-2025-47935

GHSA ID

GHSA-44fp-w29j-9vj5

Source code

Credits

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