Auth bypass in Fonoster
CVE-2026-80209
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.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (31.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 31st percentile — 31.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001
Affected products
Weakness classification (CWE)
References
- github.com/fonoster/fonoster/issues/861 (issue-tracking)
- github.com/fonoster/fonoster (product)
- github.com/fonoster/fonoster/blob/v0.22.7/mods/identity/src/workspaces/createUp… (technical-description)
- www.vulncheck.com/advisories/fonoster-through-0.22.7-incorrect-authorization-in… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-80209?
- CVE-2026-80209 is a medium-severity vulnerability in Fonoster, classified under Incorrect Authorization. CVSS score: 4.3/10. Published 2026-08-27.
- How severe is CVE-2026-80209?
- Medium severity. CVSS v3 base score is 4.3 out of 10.