Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.5.2-alpha.5 and 8.6.18, the Keycloak authentication adapter does not validate the azp (authorized party) claim of Keycloak access tokens against the configured client-id. A valid access token issued by the same Keycloak realm for a different client application can be used to authenticate as any user on the Parse Server that uses the Keycloak adapter. This enables cross-application account takeover in multi-client Keycloak realms. All Parse Server deployments that use the Keycloak authentication adapter with a Keycloak realm that has multiple client applications are affected. This vulnerability is fixed in 9.5.2-alpha.5 and 8.6.18.
Exploitability
AV:NAC:LAT:PPR:LUI:NVulnerable System
VC:HVI:HVA:NSubsequent System
SC:NSI:NSA:N7.6/CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:NAuthentication