parse-server vulnerability

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.

Published 27 Sep 2026Updated 27 Sep 20262 sources
CVSS 7.4

What happened

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 versions

parse-server: 9.0.0 through before 9.10.1-alpha.10 (semver); 8.0.2 through before 8.6.91 (semver) Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

  • Apply vendor-provided updates or mitigations.
  • Review affected product exposure and access logs.

Public PoC references

No public PoC reference has passed the current publication threshold.