CVE-2026-9589: Unblu Spark Authorization Bypass in Configuration Cascade Operations
Missing authorization in the configuration cascade operations of the Collaboration Server in Unblu inc. Unblu Spark 7.0 through 8.36.1-hotfix.0, on on-premises and cloud deployments, allows an authenticated remote attacker to read and change configuration properties of entities they aren't authorized to access, including other users, other accounts and, in Unblu Cloud, other customers' accounts, via configuration read and write operations that target those entities.
The Collaboration Server doesn't check whether the user reading or changing configuration has access to the entity the configuration belongs to. With certain non-default configuration validation settings, a registered user can additionally write configuration properties they aren't allowed to edit, in any scope.
Exploitation requires an authenticated session but no user interaction.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Unblu Sparkto a version that resolves this vulnerability.Fixed in 8.37.2
Event History
Frequently Asked Questions
Who can exploit this issue, and is user interaction required?
An attacker needs an authenticated remote session. No user interaction is required.
Which deployments and tenants may be exposed?
Both on-premises and cloud deployments are affected within the stated version range. In Unblu Cloud, an authenticated attacker may be able to read or change configuration belonging to other customers' accounts.
What access does the attacker gain through the vulnerable operations?
The attacker can use configuration read and write operations against entities they are not authorized to access, including other users and other accounts. The affected Collaboration Server does not verify that the requester has access to the entity owning the configuration.
Are ordinary registered users able to make otherwise prohibited configuration changes?
With certain non-default configuration validation settings, a registered user can write configuration properties they are not permitted to edit, in any scope. The provided information does not identify the specific settings.