CVE-2026-103091: Missing Authorization Flaw in Google SAM Scores 9.3 on CVSS
A newly published critical vulnerability in Google SAM carries a CVSS score of 9.3. Here is what is affected and how to respond.
Key points
- CVE-2026-103091 affects Google SAM.
- CVSS 9.3 (Critical).
- No exploitation confirmed yet.
A critical missing authorization tracked as CVE-2026-103091 has been published in the National Vulnerability Database for Google SAM, with a CVSS base score of 9.3.
At a glance
- CVE
- CVE-2026-103091
- Product
- Google SAM
- CVSS
- 9.3 Critical
- Weakness
- missing authorization
- Exploited
- No known exploitation
What is the vulnerability?
The NVD entry states: Missing Authorization (CWE-862) and Initialization of a Resource with an Insecure Default (CWE-1188) in the MCP proxy (HandleStreamPassThrough in mcp_service.go) and OIDC registration flow (GET /info and POST /register in internal/controlplane/server.go) in Google OSS Agent Mesh (SAM) versions 0.1.0-alpha.1 through 0.1.0-alpha.8 allow a remote attacker to self-enroll into the mesh and invoke arbitrary tools across all connected MCP backend nodes. Because GET /info publicly discloses OIDC configuration, POST /register auto-enrolls any valid OIDC token holder without claim filtering or ban checks, and the default policy binds sam:system:authenticated to wildcard services and targets, an attacker can obtain a mesh credential with full read, write, and execution access on backend services. Users should upgrade to version 0.1.0-alpha.9 or later, which enforces a fail-closed default policy, ex
Affected versions
| Vendor | Product | Versions |
|---|---|---|
| SAM | before 0.1.0-alpha.9 |
Is it being exploited?
There is no public confirmation of exploitation at the time of publication. It does not appear in CISA's Known Exploited Vulnerabilities catalog. We will update this report if that changes.
What should you do?
- Identify whether the affected product and versions run in your environment.
- Apply the vendor update listed in the advisory as soon as it is available.
- Limit network exposure of the affected service until it is patched.
- Monitor the vendor advisory for updated guidance or exploitation reports.
What to do and how to stay safe: CVE-2026-103091
- Vulnerability severity scores ignore your specific architecture and context.
- Exploitability depends on network exposure and user behavior, not just code flaws.
- Prioritization requires continuous asset inventory and threat intelligence alignment.
Risk-based vulnerability management focuses your limited resources on the flaws that actually threaten your business. Start by mapping your critical assets and checking for active exploits to prioritize your backlog.
Step-by-step guide: Risk-Based Vulnerability Management: Prioritize Fixes by Actual Danger
General security guidance from the Threat Times newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
What is CVE-2026-103091?
CVE-2026-103091 is a missing authorization vulnerability in Google SAM.
How severe is CVE-2026-103091?
It has a CVSS score of 9.3 Critical.
Is CVE-2026-103091 being exploited?
There is no public confirmation of exploitation at the time of publication.
