CVE-2026-31901

Description

### Impact The email verification endpoint (`/verificationEmailRequest`) returns distinct error responses depending on whether an email address belongs to an existing user, is already verified, or does not exist. An attacker can send requests with different email addresses and observe the error codes to determine which email addresses are registered in the application. This is a user enumeration vulnerability that affects any Parse Server deployment with email verification enabled (`verifyUserEmails: true`). ### Patches The fix introduces a new Parse Server option `emailVerifySuccessOnInvalidEmail` (default: `true`) that returns a generic success response for all verification email requests, regardless of whether the email address is valid, already verified, or non-existent. This prevents an attacker from distinguishing between these cases. The fix also strengthens the input validation for the related `resetPasswordSuccessOnInvalidEmail` option, and adds security checks that warn when either enumeration mitigation is disabled. ### Workarounds There is no known workaround. ### References - GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-w54v-hf9p-8856 - Fix Parse Server 9: https://github.com/parse-community/parse-server/releases/tag/9.6.0-alpha.8 - Fix Parse Server 8: https://github.com/parse-community/parse-server/releases/tag/8.6.34

How to fix CVE-2026-31901

To remediate CVE-2026-31901, upgrade the affected package to a fixed version below.

• —upgrade to 8.6.34 or later
• —upgrade to 9.6.0-alpha.8 or later

Is CVE-2026-31901 being exploited?

Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.

Affected packages (2)

• from 0, < 8.6.34, >= 9.0.0, < 9.6.0
• >= 9.0.0-alpha.1, < 9.6.0-alpha.8

CVSS scores

References (5)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2026-31901
• PATCHgithub.com/parse-community/parse-server
• WEBgithub.com/parse-community/parse-server/releases/tag/8.6.34
• WEBgithub.com/parse-community/parse-server/releases/tag/9.6.0-alpha.8