Description
Not Failing Securely ('Failing Open') vulnerability in livebook-dev livebook allows an unauthenticated network client to obtain full access to a Livebook server that enforces identity through Livebook Teams.

A Livebook Agent or App Server connected to Livebook Teams caches the identifier of the deployment group it belongs to, and resolves that identifier against a locally cached list of deployment groups on every request in order to decide whether Teams identity enforcement is active. Livebook.Hubs.TeamClient.handle_call/3 in lib/livebook/hubs/team_client.ex does not distinguish a deployment group that could not be resolved from one that was resolved with identity enforcement switched off: the clause matches only the case where a group was found with enforcement enabled, and falls through to a catch-all that reports enforcement as switched off for everything else. The two neighbouring functions that decide user and application access resolve the same identifier and treat the same unresolved result as a denial.

When the identity status is reported as switched off, Livebook.ZTA.LivebookTeams.authenticate/3 in lib/livebook/zta/livebook_teams.ex returns empty identity metadata and allows the request to continue instead of halting it. LivebookWeb.UserPlug.build_current_user/3 merges that empty metadata into a newly built user, whose access type defaults to full access, and LivebookWeb.AuthPlug.authorized?/1 grants access to any user holding full access.

The cached identifier becomes unresolvable when the deployment group it refers to is deleted while the agent is not connected to receive the change, most concretely when a deployment group is deleted during the window in which an agent is disconnected or reconnecting. The client removes the group from its cached list without clearing the identifier that refers to it. Any client able to reach the affected server over the network is then granted the same access as a fully privileged member of the organisation, including the ability to read notebooks and configured secrets, execute code on the server's runtime, and disrupt its operation.

This issue affects livebook: from 0.19.7 before 0.19.9.
Published: 2026-08-05
Score: 7.7 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

The vulnerability is a ‘Failing Open’ flaw that allows an unauthenticated network client to obtain full access to a Livebook server that relies on Livebook Teams for identity enforcement. The flaw arises when the deployment group identifier cached by an agent or app server cannot be resolved, causing the identity check to report enforcement as switched off. The server then creates an empty identity record, grants full access to the user, and allows the client to read notebooks, secrets, execute code, and potentially disrupt the server. The weakness is classified as CWE‑636, which describes failures of input validation leading to unrestricted access.

Affected Systems

Livebook (livebook‑dev:livebook) versions from 0.19.7 through 0.19.8 inclusive, when configured with Livebook Teams identity enforcement. Any deployment that deletes a deployment group while an agent is disconnected or reconnecting is susceptible.

Risk and Exploitability

The CVSS score of 7.7 indicates high severity. The EPSS score is not available, but the attack can be carried out by any client that can reach the server over the network. The vulnerability is not listed in CISA KEV at this time. An attacker does not need privileged credentials; the flaw allows bypass of authentication entirely, yielding full system access. The risk is significant because the affected servers grant users the ability to read confidential data and execute arbitrary code.

Generated by OpenCVE AI on August 5, 2026 at 22:08 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Upgrade Livebook to version 0.19.9 or later, which releases a fix for the failing‑open identity check.
  • After upgrading, ensure all agents reconnect so that cached deployment group identifiers are refreshed and any unresolved groups are cleared.
  • Temporarily disable Livebook Teams identity enforcement on the server until the patch is applied to prevent unauthenticated access.

Generated by OpenCVE AI on August 5, 2026 at 22:08 UTC.

Tracking

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Advisories

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History

Wed, 05 Aug 2026 20:15:00 +0000

Type Values Removed Values Added
Description Not Failing Securely ('Failing Open') vulnerability in livebook-dev livebook allows an unauthenticated network client to obtain full access to a Livebook server that enforces identity through Livebook Teams. A Livebook Agent or App Server connected to Livebook Teams caches the identifier of the deployment group it belongs to, and resolves that identifier against a locally cached list of deployment groups on every request in order to decide whether Teams identity enforcement is active. Livebook.Hubs.TeamClient.handle_call/3 in lib/livebook/hubs/team_client.ex does not distinguish a deployment group that could not be resolved from one that was resolved with identity enforcement switched off: the clause matches only the case where a group was found with enforcement enabled, and falls through to a catch-all that reports enforcement as switched off for everything else. The two neighbouring functions that decide user and application access resolve the same identifier and treat the same unresolved result as a denial. When the identity status is reported as switched off, Livebook.ZTA.LivebookTeams.authenticate/3 in lib/livebook/zta/livebook_teams.ex returns empty identity metadata and allows the request to continue instead of halting it. LivebookWeb.UserPlug.build_current_user/3 merges that empty metadata into a newly built user, whose access type defaults to full access, and LivebookWeb.AuthPlug.authorized?/1 grants access to any user holding full access. The cached identifier becomes unresolvable when the deployment group it refers to is deleted while the agent is not connected to receive the change, most concretely when a deployment group is deleted during the window in which an agent is disconnected or reconnecting. The client removes the group from its cached list without clearing the identifier that refers to it. Any client able to reach the affected server over the network is then granted the same access as a fully privileged member of the organisation, including the ability to read notebooks and configured secrets, execute code on the server's runtime, and disrupt its operation. This issue affects livebook: from 0.19.7 before 0.19.9.
Title Livebook Teams identity check fails open when the deployment group is unresolvable, allowing unauthenticated access
First Time appeared Livebook-dev
Livebook-dev livebook
Weaknesses CWE-636
CPEs cpe:2.3:a:livebook-dev:livebook:*:*:*:*:*:*:*:*
Vendors & Products Livebook-dev
Livebook-dev livebook
References
Metrics cvssV4_0

{'score': 7.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}

Subscriptions

Livebook-dev Livebook
cve-icon MITRE

Status: PUBLISHED

Assigner: EEF

Published:

Updated: 2026-08-05T19:43:38.188Z

Reserved: 2026-07-31T13:23:00.354Z

Link: CVE-2026-68746

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-05T22:15:04Z

Weaknesses
  • CWE-636

    Not Failing Securely ('Failing Open')