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HIGH

Parse Server 9.0.0 Authentication Bypass via Unverified Provider Identity

Published Sep 27, 2026

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

Remediation

No remediation recorded yet.

References (3)

Change history (0)

No recorded changes yet.

Sources
CVE.org / MITRE
Status PUBLISHED
Assigner VulnCheck
Published Sep 27, 2026
Updated Sep 30, 2026
Reserved Sep 27, 2026
CISA Vulnrichment
Updated Sep 30, 2026
NVD
Status Received
Modified Sep 27, 2026
Red Hat
Severity n/a
Public date n/a
ENISA EUVD
Assigner VulnCheck
Published Sep 27, 2026
Updated Sep 30, 2026
Exploited since n/a
EUVD-2026-87968