draw.io: OAuth CSRF via missing state validation on self-hosted deployments allows session token injection

Summary

draw.io is a configurable diagramming and whiteboarding application. Prior to version 30.2.7, the OAuth callback handler in src/main/java/com/mxgraph/online/AbsAuth.java skips comparison of stateToken and cookieToken whenever IS_GAE is false, which affects self-hosted Docker and WAR deployments. An attacker can provide an authorization code for the attacker's cloud-storage identity and induce a victim to visit a callback URL, causing the victim's draw.io session to become authenticated as the attacker identity without a valid state binding. The shared handler affects Google Drive, OneDrive, GitHub, GitLab, and Dropbox integrations. The victim can then unknowingly perform cloud-storage actions under the attacker's identity, causing session integrity loss and misattribution, but the identity binding does not itself grant access to existing victim cloud files. This issue is fixed in version 30.2.7.