Information Exposure Through Timing Discrepancy in Parse Server - CVE-2026-39321

Vulnerability details

The vulnerability allows a remote attacker to enumerate valid usernames or email addresses.

The vulnerability exists due to observable timing discrepancy in the login endpoint when processing login requests with submitted usernames or email addresses. A remote attacker can send login attempts with incorrect passwords and measure response times to enumerate valid usernames or email addresses.

Accounts without a stored password, such as OAuth-only accounts, are also affected by the timing side channel.

Affected software

How to mitigate CVE-2026-39321

External References

• https://github.com/parse-community/parse-server/security/advisories/GHSA-mmpq-5hcv-hf2v

Related Security Bulletins

• Information Exposure Through Timing Discrepancy in Parse Server