# CVE-2015-9240: KeystoneJS Keystone authentication bypass via partial email matching

Source: https://junglewise.ai/threats/cve-2015-9240-keystonejs-keystone-authentication-bypass-via-partial-email  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2018-06-07. Updated: 2026-05-14  
License: CC BY 4.0 with a link back

CVE-2015-9240 · Severity: low · CVSS 3 · Published 2018-06-07

Keystone, a popular Node.js content management system and web framework, contains a flaw in its default login system. An attacker who knows a user's password can successfully log in even if they only provide a partial or incomplete email address. This could allow unauthorized access to administrative accounts if an attacker can guess or obtain passwords and use shortened versions of target email addresses.

Technologies: [KeystoneJS](https://junglewise.ai/threats/technologies/keystone-5). Vendors: [KeystoneJS](https://junglewise.ai/threats/vendors/keystonejs).

## Quick answers

**Is CVE-2015-9240 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2015-9240 being exploited in the wild.

**How severe is CVE-2015-9240?** Low severity, with a CVSS score of 3, published 7 June 2018.

**Which products and versions are affected?** KeystoneJS < 0.3.16.

**Is there a fix for CVE-2015-9240?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2015-9240 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2015-9240?** Check whether you run KeystoneJS 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

A vulnerability in the default sign-in functionality of the Keystone node module (prior to version 0.3.16) allows for a partial authentication bypass. The root cause is a bug in the email matching logic where incomplete email addresses are incorrectly validated against the database. While a correct password is still required for authentication, an attacker can gain access by providing only a substring or partial match of a valid user's email address. This is reachable over the network without prior authentication. The issue was addressed in version 0.3.16.

## Affected products

- KeystoneJS keystone < 0.3.16

## Identifiers

- CVE-2015-9240
- GHSA-39pj-gq8q-9pfj

## Timeline

- 2015-01-01: other: Vulnerability identified (based on CVE year)
- 2018-05-29: disclosed: NVD Published Date
- 2018-06-07: advisory: GitHub Advisory published

## References

- [https://www.npmjs.com/advisories/60](https://www.npmjs.com/advisories/60)
- [https://www.npmjs.com/package/keystone](https://www.npmjs.com/package/keystone)

## Related threats

- [KeystoneJS @keystone-6/core incorrect NODE_ENV inlining via esbuild](https://junglewise.ai/threats/cve-2022-39382-keystonejs-keystone-6-core-incorrect-node-env-inlining-via)