CVE-2026-39321

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

CVSS 6.3 MEDIUMEPSS 0.2%CWE-208

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.

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Affected products

parse-community · parse-server

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References

https://github.com/parse-community/parse-server/pull/10398 https://github.com/parse-community/parse-server/pull/10399 https://github.com/parse-community/parse-server/security/advisories/GHSA-mmpq-5hcv-hf2v