# CVE-2026-8162: Pillarjs multiparty denial of service via uncaught exception

Source: https://junglewise.ai/threats/cve-2026-8162-pillarjs-multiparty-denial-of-service-via-uncaught-exception  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-12. Updated: 2026-05-18  
License: CC BY 4.0 with a link back

CVE-2026-8162 · Severity: high · CVSS 7.5 · Published 2026-05-12

A vulnerability in the multiparty library, which is used to handle file uploads in web applications, can allow an attacker to crash the server. By sending a specially crafted file upload request, an attacker can trigger an unhandled error that shuts down the application process. This results in a denial of service, making the application unavailable to legitimate users.

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

## Quick answers

**Is CVE-2026-8162 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-8162 being exploited in the wild.

**How severe is CVE-2026-8162?** High severity, with a CVSS score of 7.5, published 12 May 2026.

**Which products and versions are affected?** multiparty (npm) SEMVER:introduced=0,fixed=4.3.0; Pillarjs Multiparty <= 4.2.3.

**Is there a fix for CVE-2026-8162?** Yes. multiparty (npm): upgrade to 4.3.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-8162 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-8162?** Check whether you run multiparty (npm) or 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.

## How to fix

- multiparty (npm): upgrade to 4.3.0 or later

  ```sh
  npm install multiparty@4.3.0
  ```


## Technical details

The multiparty library (versions 4.2.3 and earlier) fails to properly handle exceptions during the parsing of the 'filename*' parameter in 'Content-Disposition' headers. When a request contains malformed percent-encoding (e.g., '%FF'), the parser calls the JavaScript 'decodeURI' function without a try/catch block. This results in a 'URIError' that propagates as an uncaught exception, crashing the Node.js process. An unauthenticated remote attacker can exploit this by sending a single malicious multipart/form-data request. The issue is resolved in version 4.3.0.

## Affected products

- pillarjs multiparty <= 4.2.3

## Identifiers

- CVE-2026-8162
- GHSA-xh3c-6gcq-g4rv

## Timeline

- 2026-05-12: disclosed: NVD publication date
- 2026-05-18: advisory: GitHub Advisory published
- 2026-05-18: patched: Version 4.3.0 released

## References

- [https://api.github.com/users/ByamB4](https://api.github.com/users/ByamB4)
- [https://github.com/ByamB4](https://github.com/ByamB4)
- [https://api.github.com/users/ByamB4/gists%7B/gist_id%7D](https://api.github.com/users/ByamB4/gists%7B/gist_id%7D)
- [https://api.github.com/users/ByamB4/repos](https://api.github.com/users/ByamB4/repos)
- [https://avatars.githubusercontent.com/u/43212232?v=4](https://avatars.githubusercontent.com/u/43212232?v=4)
- [https://api.github.com/users/ByamB4/events%7B/privacy%7D](https://api.github.com/users/ByamB4/events%7B/privacy%7D)

## Related threats

- [multiparty denial of service via unbounded part-header accumulation](https://junglewise.ai/threats/cve-2026-87908-multiparty-denial-of-service-via-unbounded-part-header)
- [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)