Parse Server has a login timing side-channel reveals user existence

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

• CISA KEV Not listed.
• EPSS 0.0024, the 15th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the GitHub Advisory Database, published 8 Apr 2026. New records show when each source confirmed them.

Sources

• GitHub Advisory Database: GHSA-mmpq-5hcv-hf2v
• OSV: GHSA-mmpq-5hcv-hf2v
• github.com/parse-community/parse-server/security/advisories/GHSA-mmpq-5hcv-hf2v
• nvd.nist.gov/vuln/detail/CVE-2026-39321
• github.com/parse-community/parse-server/pull/10398
• github.com/parse-community/parse-server/pull/10399
• github.com/parse-community/parse-server

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.