CVE-2026-39321 Parse Server has a login timing side-channel reveals user existence
An unauthenticated attacker can enumerate valid usernames by measuring response time differences in the login endpoint.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-39321?
CVE-2026-39321 is a medium-severity vulnerability in Parseplatform Parse-Server, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.8.0-alpha.6 and 8.6.74, he login endpoint response time differs measurably depending on whether the submitted username or email exists in the database. When a user is not found, the server responds immediately. When a user exists but the password is wrong, a bcrypt comparison runs first, adding significant latency. This timing difference allows an unauthenticated attacker to enumerate valid usernames. This vulnerability is fixed in 9.8.0-alpha.6 and 8.6.74.
Weakness: CWE-208
Which versions are affected by CVE-2026-39321?
5 open source packages ship an affected version, including parse-server and parse. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
parse-server npm | All versions | 8.6.74 |
parse-server npm | All versions | 8.6.74 |
parse-server npm | From 9.0.0 | 9.8.0-alpha.6 |
parse-server npm | From 9.0.0 | 9.8.0-alpha.6 |
parse Bitnami | All versions | 8.6.74, 9.8.0 |
Products include Parseplatform Parse-Server.
How do I fix CVE-2026-39321?
Upgrade parse-server to a fixed version for your release line: 8.6.74 or 9.8.0-alpha.6.
Is CVE-2026-39321 being exploited?
There is no known exploitation of CVE-2026-39321 in the wild and no public exploit code.
Other vulnerabilities in Parseplatform Parse-Server
- CVE-2026-30966 Parse Server role escalation and CLP bypass via direct `_Join` table write
- CVE-2024-27298 Parse Server literalizeRegexPart SQL Injection
- CVE-2022-24760 Command Injection in Parse server
- CVE-2026-30965 Parse Server session token exfiltration via `redirectClassNameForKey` query parameter
- CVE-2023-36475 Parse Server vulnerable to remote code execution via MongoDB BSON parser through prototype pollution
Sources
Also known as BIT-parse-2026-39321, GHSA-mmpq-5hcv-hf2v.