The vulnerability arises in livebook-dev livebook when configured to use Livebook Teams for identity. The OAuth-style callback handler exchanges an authorization code for an access token and writes it into the victim's browser session without verifying any state or nonce that would link the callback to the original login request. Since no per-attempt state is generated or checked, an attacker who is a member of the same Livebook Teams organization can initiate a login flow, obtain an authorization code, and trick a victim into redeeming that code. This causes the victim's session to be authenticated as the attacker’s identity, not the victim’s. The victim is unaware and operates under the attacker’s account, exposing any work, secrets, or data to the attacker. The attack is constrained by the short validity window of the authorization code but is otherwise feasible.

The vulnerability allows an attacker to cause a victim's browser session to be authenticated as the attacker’s Livebook Teams identity. This means that any work, uploaded data, or notebook results produced by the victim during that session are attributed to and accessible by the attacker. The victim does not authenticate as the attacker, but rather unknowingly operates under the attacker's identity, leading to potential data exposure and misattribution of actions. The attack requires the attacker to be a member of the same Livebook Teams organization and to induce the victim to open a crafted URL within a short time window.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should be cautious about opening unsolicited URLs related to Livebook Teams login flows. Monitoring for updates from livebook-dev regarding patches or mitigations is recommended.