CVE-2026-101042: Parse Server 9.0.0 Authentication Bypass via Unverified Provider Identity

Severity: medium (CVSS 6.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-27 · updated 2026-09-30
Weakness: CWE-287

Description

Parse Server is an open-source backend server. In versions >= 9.0.0 < 9.10.1-alpha.10 and >= 8.0.2 < 8.6.91, the code-based authentication adapters (GitHub, Google Play Games, Instagram, LINE, LinkedIn, Microsoft, QQ, Spotify, WeChat, Weibo) verify the client's authorization code with the external provider on signup and on provider linking, but not when authentication data is supplied together with a username and password on the login endpoint. As a result, a low-privileged authenticated user can attach an arbitrary, unverified provider identity to their own account without the provider ever being contacted, spoofing an external identity toward application logic that trusts the linked provider ID. An attacker can also pre-hijack accounts: by claiming the provider ID of a victim who has not yet linked that provider, the victim's later legitimate sign-in with that provider resolves to the attacker's account. Only deployments configuring one of the affected code-based auth adapters are impacted. Versions 9.10.1-alpha.10 and 8.6.91 fix the issue by running the adapter's credential verification on the login and challenge endpoints and rejecting a provider identity already linked to another user. As a workaround, disable the affected code-based auth adapters.

Affected products

parse-community parse-server: from 9.0.0 before 9.10.1-alpha.10; from 8.0.2 before 8.6.91 — fixed in 8.6.91, 9.10.1-alpha.10

How to fix

Upgrade to a fixed version: parse-community parse-server 8.6.91, 9.10.1-alpha.10. Check the vendor advisory for mitigations.

References

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