CVE-2026-103091: Software Security Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-qx8v-pq9p-7g7v
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CWE-200
Published
Advisory Summary

CVE-2026-103091 is a CRITICAL security vulnerability vulnerability (CWE-200: Exposure of Sensitive Information to an Unauthorized Actor) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-103091 at a Glance

CVE Identifier CVE-2026-103091
GHSA Identifier GHSA-qx8v-pq9p-7g7v
Severity CRITICAL
CVSS v3.1 Base Score N/A
CWE Classification CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

How to Fix CVE-2026-103091

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-103091, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor, where the product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

References

GitHub Advisory / Wiki ADVISORY
https://github.com/google/agentmesh/security/advisories/GHSA-cgmg-9xf6-rrgw
GitHub Advisory / Wiki ADVISORY
https://github.com/google/sam/security/advisories/GHSA-cgmg-9xf6-rrgw
NVD — CVE-2026-103091 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-103091
Software Release RELEASE
https://github.com/google/sam/releases/tag/v0.1.0-alpha.9

Frequently Asked Questions

What is CVE-2026-103091?
CVE-2026-103091 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-103091?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What CWE is associated with CVE-2026-103091?
CVE-2026-103091 is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor (The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.).
How can I check Maven dependencies for CVE-2026-103091?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-qx8v-pq9p-7g7v",
  "modified" : "2026-10-19T18:32:06Z",
  "published" : "2026-10-19T03:31:05Z",
  "aliases" : [ "CVE-2026-103091" ],
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/google/agentmesh/security/advisories/GHSA-cgmg-9xf6-rrgw"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/google/sam/security/advisories/GHSA-cgmg-9xf6-rrgw"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-103091"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/google/sam/releases/tag/v0.1.0-alpha.9"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200" ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-10-19T03:16:58Z"
  }
}