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Fonoster CVE-2026-80209

| EUVDEUVD-2026-67143 MEDIUM
Incorrect Authorization (CWE-863)
2026-08-27 VulnCheck GHSA-xqrc-3jm3-hm6q
5.3
CVSS 4.0 · Vendor: VulnCheck
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Severity by source

Vendor (VulnCheck) PRIMARY
5.3 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
5.0 MEDIUM

Network-accessible with low privileges; scope changes because authenticated users can modify workspaces owned by other users outside their own security scope.

3.1 AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
X

Lifecycle Timeline

1
Analysis Generated
Aug 27, 2026 - 18:19 vuln.today

DescriptionCVE.org

The updateWorkspace handler in mods/identity/src/workspaces/createUpdateWorkspace.ts in Fonoster through 0.22.7 invokes the gRPC callback with PERMISSION_DENIED when createIsWorkspaceMember reports that the caller is not a member of the target workspace, but it does not return. Execution continues into prisma.workspace.update, which is scoped by the workspace reference alone, so the rename commits before the second callback is issued and the caller receives a permission error for a write that already succeeded. The gRPC interceptor in mods/common/src/identity/createAuthInterceptor.ts binds the workspace accessKeyId to the caller's token only for paths in workspaceResourceAccess or workspaceResourceOwnerOrAdminAccess, and Identity/UpdateWorkspace is listed in fullIdentityAccess, which the base USER role holds. Any authenticated user can therefore rename an arbitrary workspace in the deployment.

AnalysisAI

Incorrect authorization in Fonoster through 0.22.7 allows any authenticated user to rename arbitrary workspaces across the entire deployment. The Identity/UpdateWorkspace gRPC handler in createUpdateWorkspace.ts issues a PERMISSION_DENIED callback upon failing a membership check but omits a return statement, so prisma.workspace.update executes regardless and commits the rename before a second error callback fires. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Authenticate with any valid Fonoster USER-role token
Delivery
Enumerate or guess target workspace reference identifier
Exploit
Send gRPC UpdateWorkspace request for arbitrary workspace
Execution
Handler issues PERMISSION_DENIED but omits return
Persist
Prisma commits workspace rename to database
Impact
Caller receives error response while rename has succeeded

Vulnerability AssessmentAI

Exploitation Exploitation requires a valid authentication token for the Fonoster deployment - any user holding the base USER role is sufficient, as that role grants `fullIdentityAccess` which includes `Identity/UpdateWorkspace`. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment CVSS 4.0 scores this 5.3 (Medium) with AV:N/AC:L/AT:N/PR:L/UI:N and limited integrity impact (VI:L, no confidentiality or availability impact). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An authenticated Fonoster user with only a base USER role token crafts a gRPC `Identity/UpdateWorkspace` request targeting a workspace belonging to another organization, substituting the victim workspace's reference identifier. The handler's membership check fires and issues a PERMISSION_DENIED callback, but the missing `return` allows `prisma.workspace.update` to execute, renaming the target workspace before the error is returned. …
Remediation No vendor-released patched version has been identified at time of analysis. … Detailed patch versions, workarounds, and compensating controls in full report.

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CVE-2026-80209 vulnerability details – vuln.today

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