# CVE-2026-39321: Parse Community Parse Server timing side-channel in login endpoint

Source: https://junglewise.ai/threats/cve-2026-39321-parse-community-parse-server-timing-side-channel-in-login  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-07. Updated: 2026-05-11  
License: CC BY 4.0 with a link back

CVE-2026-39321 · Severity: low · CVSS 3.7 · Published 2026-04-07

Parse Server is an open-source backend framework used to power mobile and web applications. A vulnerability in its login system allows unauthorized individuals to determine if a specific username or email address exists in the database by measuring how long the server takes to respond. This could lead to the exposure of user lists, which can be used for targeted phishing or credential-guessing attacks.

Technologies: [parse-server (npm)](https://junglewise.ai/threats/technologies/parse-server). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-39321 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-39321 being exploited in the wild.

**How severe is CVE-2026-39321?** Low severity, with a CVSS score of 3.7, published 7 April 2026.

**Which products and versions are affected?** parse-server (npm) SEMVER:introduced=9.0.0,fixed=9.8.0-alpha.6.

**Is there a fix for CVE-2026-39321?** Yes. parse-server (npm): upgrade to 9.8.0-alpha.6 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-39321 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-39321?** Check whether you run parse-server (npm) or Parseplatform Parse-Server 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

- parse-server (npm): upgrade to 9.8.0-alpha.6 or later

  ```sh
  npm install parse-server@9.8.0-alpha.6
  ```


## Technical details

A timing side-channel vulnerability (CWE-208) exists in the Parse Server login endpoint. The server's response time varies significantly depending on whether a user exists: if a user is found, the server performs a computationally expensive bcrypt password comparison; if the user does not exist, it returns a response immediately. This discrepancy allows an unauthenticated attacker to perform username enumeration via network-based timing analysis. The issue has been addressed in versions 8.6.74 and 9.8.0-alpha.6 by implementing a dummy bcrypt comparison when a user is not found, thereby normalizing response times.

## Affected products

- Parse Community parse-server >= 9.0.0, < 9.8.0-alpha.6; < 8.6.74

## Identifiers

- CVE-2026-39321
- GHSA-mmpq-5hcv-hf2v

## Timeline

- 2026-04-05: disclosed: Initial disclosure by mtrezza
- 2026-04-07: advisory: NVD publication
- 2026-04-08: advisory: GitHub Advisory published

## References

- [https://api.github.com/users/offset](https://api.github.com/users/offset)
- [https://github.com/offset](https://github.com/offset)
- [https://api.github.com/users/offset/gists%7B/gist_id%7D](https://api.github.com/users/offset/gists%7B/gist_id%7D)
- [https://api.github.com/users/offset/repos](https://api.github.com/users/offset/repos)
- [https://avatars.githubusercontent.com/u/114768995?v=4](https://avatars.githubusercontent.com/u/114768995?v=4)
- [https://api.github.com/users/offset/events%7B/privacy%7D](https://api.github.com/users/offset/events%7B/privacy%7D)

## Related threats

- [Duplicate Advisory: Parse Server vulnerable to stored XSS via malformed Content-Type bypassing file upload extension blocklist](https://junglewise.ai/threats/duplicate-advisory-parse-server-vulnerable-to-stored-xss-via-malformed-00d8867c)
- [Parse Server stored XSS via malformed Content-Type bypass](https://junglewise.ai/threats/cve-2026-61448-parse-server-stored-xss-via-malformed-content-type-bypass)
- [Parse Server information disclosure in LiveQuery ACL transitions](https://junglewise.ai/threats/cve-2026-57481-parse-server-information-disclosure-in-livequery-acl-transitions)
- [Parse Community Parse Server denial of service via nested query operators](https://junglewise.ai/threats/cve-2026-57480-parse-community-parse-server-denial-of-service-via-nested-query)
- [Parse Server stored XSS via file upload extension bypass](https://junglewise.ai/threats/cve-2026-55778-parse-server-stored-xss-via-file-upload-extension-bypass)