CVE-2026-87908: multiparty vulnerable to Denial of Service via unbounded part-header accumulation
multiparty is a Node.js library for parsing multipart/form-data request bodies. In versions from 2.1.0 up to but not including 4.3.1, the parser does not bound the amount of memory used while accumulating the headers of a single multipart part. An unauthenticated attacker can send a single request whose part carries a very large volume of header bytes, forcing the parser to buffer all of them and exhausting the process memory, which crashes the server. This is a denial of service with no confidentiality or integrity impact. The issue is fixed in multiparty 4.3.1, which caps the size of the accumulated part headers. Users should upgrade to multiparty 4.3.1 or later.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
multipartyto a version that resolves this vulnerability.Fixed in 4.3.1
Event History
Frequently Asked Questions
Which deployments are exposed to this issue?
Applications using multiparty versions 2.1.0 through 4.3.0 to parse multipart/form-data request bodies are affected. The issue can be reached over the network when an attacker can submit a multipart request to the application.
Does an attacker need authentication or user interaction?
No. An unauthenticated attacker can trigger the issue with a single crafted request, and no user interaction is required.
What is the impact of successful exploitation?
A malicious multipart part can contain a very large volume of header bytes, causing multiparty to consume process memory while buffering them. Exhausting memory can crash the server; the provided information indicates no confidentiality or integrity impact.
What version should be deployed to remediate the issue?
Upgrade multiparty to version 4.3.1 or later. Version 4.3.1 caps the size of accumulated multipart part headers.