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CriticalVulnerabilityCVE-2026-9589updated 25 Oct 2026, 15:20 UTC

Unblu Collaboration Server lets logged-in users read and change others' settings

A user with a normal login can view and change configuration belonging to other users, accounts, and in the cloud version, other customers. This can expose private settings and alter how other people's accounts behave.

Official, 2 sources
SeverityCriticalCVSS 9.3 of 10
Being exploited?UnclearNo reports either way yet
Fix available?UnclearNo fixed version published in the sources yet
How sure is this?Official, 2 sourcesBacked by an official source

How the attack works simplified

  1. 1Valid loginAny registered user account is enough
  2. 2Collaboration ServerConfig operations skip access checks
  3. 3Other entities' configRead or change other users' settings
  4. 4Other customersCloud deployments can cross tenant boundaries
  5. ResultAttacker reads or alters others' configuration

What happened

Missing authorization checks in the configuration cascade operations of Unblu Spark's Collaboration Server allow authenticated users to read and write configuration properties of entities they are not authorized to access. With certain non-default validation settings, registered users can also write properties in any scope.

Why it is dangerous: An attacker with any valid account can access and modify other users' and accounts' configuration, and in Unblu Cloud, other customers' accounts, without user interaction.

Are you affected?

You are affected if you run Unblu Spark versions 7.0 through 8.36.1-hotfix.0, either on-premises or in Unblu Cloud.

Unblu Spark 7.0 through 8.36.1-hotfix.0 (on-premises and cloud deployments)

What to do

  1. Check with Unblu or your vendor contact for the fixed version or official mitigation for CVE-2026-9589
  2. Review who has user accounts on your Unblu Spark instance and remove unnecessary ones
  3. Monitor configuration changes on the Collaboration Server for unexpected activity

Timeline

  1. 20 Oct 2026, 11:17 UTC
    Publicly disclosed
  2. 20 Oct 2026, 11:17 UTC
    Reported by NVD · NVD
  3. 25 Oct 2026, 15:20 UTC
    GitHub Advisory reported on it · GitHub Advisory

Sources 2 reports, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-9589 · GHSA-m9mc-chm4-qcpm
CVSS
9.3 / 10
EPSS
0.4% chance of exploitation within 30 days
Disclosed
20 Oct 2026, 11:17 UTC
On Zero Radar
before the radar started
Last change
25 Oct 2026, 15:20 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

Unblu Collaboration Server lets logged-in users read and change others' settings · Zero Radar