Low severity · published Apr 7, 2026
CVE-2026-39321
Parse Server has a login timing side-channel reveals user existence
3.7
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 14% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PA
parse-server · parse-community
>= 9.0.0, < 9.8.0-alpha.6; < 8.6.74 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-39321
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-39321
Issue Tracking
https://github.com/parse-community/parse-server/pull/10398
Issue Tracking
https://github.com/parse-community/parse-server/pull/10399
Mitigation
https://github.com/parse-community/parse-server/security/advisories/GHSA-mmpq-5hcv-hf2v
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