VulnTideExploited vulnerabilities, by vendor. Data as of .
Not in CISA KEVPublished CVSS 9.3 criticalEPSS 0.6% probability of exploitation in 30 days
Google

CVE-2026-103091: Insecure Default Policy and Unrestricted OIDC Enrollment in Google OSS Agent Mesh (SAM)

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.

How likely is exploitation in the next 30 days?
0.6%

EPSS score, percentile 50.7 of all scored records. A probability estimated by FIRST, not a report of exploitation.

CISA's SSVC assessment in the CVE record lists exploitation as poc.

How severe?
9.3 Critical

CVSS v4.0 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (2)

Which versions are affected?

Affected

  • from 0.1.0-alpha.1 to before 0.1.0-alpha.9

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of ; CVE List V5 (CVE Program), cve_2026-10-29_0000Z, as of . About the data.

What to do

Advisories and patches

Affected products and versions

As listed in the CVE record.

Google SAM
StatusVersions
Affectedfrom 0.1.0-alpha.1 to before 0.1.0-alpha.9

Versions not listed are: unaffected.

Source: CVE List V5 (CVE Program), cve_2026-10-29_0000Z, as of . About the data.

About this vulnerability

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 arbi…

Summary: CVE record, as of .

  • CISA has not added CVE-2026-103091 to its Known Exploited Vulnerabilities (KEV) catalog, as of 28 Oct 2026.
  • The CVE record was published on 19 Oct 2026.
  • The CVE record carries a CVSS v4.0 base score of 9.3 (Critical), given by its CNA.
  • FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.6% (percentile 50.7), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
  • CISA's SSVC assessment in the CVE record: exploitation poc, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; CVE List V5 (CVE Program), cve_2026-10-29_0000Z, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of . About the data.

Description

Insecure Default Policy and Unrestricted OIDC Enrollment in Google OSS Agent Mesh (SAM)

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, explicit policy-binding requirements on enrollment, and ban checks.

Source: CVE List V5 (CVE Program), cve_2026-10-29_0000Z, as of . About the data.

Weakness

  • CWE-862: Missing Authorization
  • CWE-1188: Initialization of a Resource with an Insecure Default
  • CWE-306: Missing Authentication for Critical Function
  • CWE-863: Incorrect Authorization
  • CWE-200: Exposure of Sensitive Information to an Unauthorized Actor

Attack patterns (CAPEC)

  • CAPEC-180: Exploiting Incorrectly Configured Access Control Security Levels
  • CAPEC-122: Privilege Abuse

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.

Timeline

DateEvent
CVE record published

Known exploited Google vulnerabilities

  • CVE-2026-111497: Google Brotli Unchecked Return Value Vulnerability (added )
  • CVE-2026-58704: Google Pixel Improper Authorization Vulnerability (added )
  • CVE-2026-87491: Google Chromium V8 Out of Bounds Write Vulnerability (added )
  • CVE-2026-85046: Google Chromium V8 Type Confusion Vulnerability (added )
  • CVE-2026-11645: Google Chromium V8 Out-of-Bounds Read and Write Vulnerability (added )