# CVE-2026-87908: multiparty denial of service via unbounded part-header accumulation

Source: https://junglewise.ai/threats/cve-2026-87908-multiparty-denial-of-service-via-unbounded-part-header  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-11. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-87908 · Severity: high · CVSS 7.5 · Published 2026-09-11

multiparty is a Node.js library used to parse file uploads and form data in web applications. An attacker can send a specially crafted upload request with extremely large headers that causes the server to consume all available memory and crash, taking the service offline. No data is compromised, but legitimate users lose access to the application.

Technologies: [Pillarjs Multiparty](https://junglewise.ai/threats/technologies/multiparty). Vendors: [Pillarjs](https://junglewise.ai/threats/vendors/pillarjs).

## Quick answers

**Is CVE-2026-87908 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-87908 being exploited in the wild.

**How severe is CVE-2026-87908?** High severity, with a CVSS score of 7.5, published 11 September 2026.

**Which products and versions are affected?** Pillarjs Multiparty 2.1.0 to 4.3.0.

**Is there a fix for CVE-2026-87908?** A patch was published on 2026-09-11: Fixed in version 4.3.1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-87908 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-87908?** Check whether you run Pillarjs Multiparty at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

This is a denial-of-service vulnerability caused by uncontrolled memory allocation in the multipart header parsing logic. The library bounds field values (maxFieldsSize) and file bytes (maxFilesSize), but fails to limit the size of individual part headers. An unauthenticated attacker can craft a multipart/form-data request with a header that never terminates, forcing the parser to buffer all bytes until the process exhausts available memory and crashes. This applies even when all documented limits are configured. The vulnerability affects versions 2.1.0 through 4.3.0; it is fixed in version 4.3.1, which introduces a maxHeadersSize option (default 16 KB) to cap per-part header accumulation.

## Affected products

- pillarjs multiparty 2.1.0 to 4.3.0

## Timeline

- 2026-09-11: disclosed
- 2026-09-11: patched: Fixed in version 4.3.1

## References

- [https://cna.openjsf.org/security-advisories.html](https://cna.openjsf.org/security-advisories.html)
- [https://github.com/pillarjs/multiparty/security/advisories/GHSA-5h46-2939-q3wh](https://github.com/pillarjs/multiparty/security/advisories/GHSA-5h46-2939-q3wh)

## Related threats

- [Pillarjs multiparty denial of service via uncaught exception](https://junglewise.ai/threats/cve-2026-8162-pillarjs-multiparty-denial-of-service-via-uncaught-exception)
- [multiparty denial of service via prototype pollution](https://junglewise.ai/threats/cve-2026-8161-multiparty-denial-of-service-via-prototype-pollution)
- [Pillarjs multiparty ReDoS in Content-Disposition filename parser](https://junglewise.ai/threats/cve-2026-8159-pillarjs-multiparty-redos-in-content-disposition-filename-parser)