{"id":"GHSA-mmpq-5hcv-hf2v","summary":"Parse Server has a login timing side-channel reveals user existence","details":"### Impact\n\nThe 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.\n\n### Patches\n\nA dummy bcrypt comparison is now performed when no user is found, normalizing response timing regardless of user existence. Additionally, accounts without a stored password (e.g. OAuth-only) now also run a dummy comparison to prevent the same timing oracle.\n\n### Workarounds\n\nConfigure rate limiting on the login endpoint to slow automated enumeration. This reduces throughput but does not eliminate the timing signal for individual requests.","aliases":["BIT-parse-2026-39321","CVE-2026-39321"],"modified":"2026-04-15T21:34:44.865456Z","published":"2026-04-08T00:07:10Z","database_specific":{"github_reviewed_at":"2026-04-08T00:07:10Z","nvd_published_at":"2026-04-07T18:16:43Z","cwe_ids":["CWE-208"],"severity":"MODERATE","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/parse-community/parse-server/security/advisories/GHSA-mmpq-5hcv-hf2v"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-39321"},{"type":"WEB","url":"https://github.com/parse-community/parse-server/pull/10398"},{"type":"WEB","url":"https://github.com/parse-community/parse-server/pull/10399"},{"type":"PACKAGE","url":"https://github.com/parse-community/parse-server"}],"affected":[{"package":{"name":"parse-server","ecosystem":"npm","purl":"pkg:npm/parse-server"},"ranges":[{"type":"SEMVER","events":[{"introduced":"9.0.0"},{"fixed":"9.8.0-alpha.6"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-mmpq-5hcv-hf2v/GHSA-mmpq-5hcv-hf2v.json"}},{"package":{"name":"parse-server","ecosystem":"npm","purl":"pkg:npm/parse-server"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"8.6.74"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-mmpq-5hcv-hf2v/GHSA-mmpq-5hcv-hf2v.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N"},{"type":"CVSS_V4","score":"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"}]}