CVE-2026-7428: Google Cloud AlloyDB Auth Bypass Flaw

CVE-2026-7428 Overview

CVE-2026-7428 affects Google Cloud AlloyDB for PostgreSQL clusters provisioned through Terraform or the REST API before 2025-11-03. The provisioning workflow accepted an insecure default password, allowing remote attackers with network access to the cluster to authenticate as a privileged user. Successful exploitation granted full administrative access to the database, including read, write, and configuration control. Other AlloyDB clients blocked the insecure default and were not affected. Google addressed the issue and documented the fix in the AlloyDB release notes.

Critical Impact
Remote attackers with network reach to affected AlloyDB clusters could authenticate using a predictable default password and obtain full administrative control of the PostgreSQL database.

Affected Products

Google Cloud AlloyDB for PostgreSQL clusters created via Terraform prior to 2025-11-03
Google Cloud AlloyDB for PostgreSQL clusters created via REST API prior to 2025-11-03
AlloyDB cluster administrative database accounts using the insecure default password

Discovery Timeline

2026-05-12 - CVE-2026-7428 published to NVD
2026-05-12 - Last updated in NVD database

Technical Details for CVE-2026-7428

Vulnerability Analysis

The vulnerability is classified under [CWE-1392] Use of Default Credentials. When users created AlloyDB clusters through Terraform or the REST API, the provisioning pipeline did not enforce a strong password on the initial administrative account. The cluster accepted a known default value, which an attacker could supply during authentication. The flaw was scoped to specific provisioning paths. Standard AlloyDB clients rejected the same configuration, which limited the exposure surface to infrastructure-as-code and direct API workflows. The issue is a configuration and design flaw rather than a code execution bug in the database engine itself.

Root Cause

The root cause is an insecure default configuration in the AlloyDB cluster creation flow exposed by Terraform and the REST API. The provisioning path did not require operators to supply a unique, high-entropy password for the administrative user. Clusters were therefore created with credentials an external party could predict or reproduce.

Attack Vector

Exploitation required network access to the target AlloyDB cluster. An attacker who reached the database endpoint could connect as the administrative user using the default password. No prior authentication was required, and the attack ran without user interaction. Successful login granted full read, write, and administrative control over the PostgreSQL database hosted in AlloyDB.

No public proof-of-concept code is associated with this CVE. See the Google Cloud AlloyDB release notes for vendor remediation details.

Detection Methods for CVE-2026-7428

Indicators of Compromise

Successful PostgreSQL authentication events on AlloyDB clusters from unexpected source IP ranges outside known administrator networks.
AlloyDB clusters provisioned via Terraform or REST API before 2025-11-03 that have not had their administrative password rotated.
Unexpected creation of database roles, extensions, or superuser-level objects following cluster provisioning.
Audit log entries showing administrative actions originating from sessions established without prior credential management activity.

Detection Strategies

Inventory all AlloyDB clusters and identify those created through Terraform or REST API calls prior to 2025-11-03.
Review Google Cloud Audit Logs for AlloyDB authentication events and correlate source IPs against approved administrator and application identities.
Hunt for PostgreSQL role modifications, replication setup, or pg_dump-style bulk read activity on affected clusters.
Cross-reference Terraform state files and CI/CD pipelines for hardcoded or default password values used during AlloyDB cluster creation.

Monitoring Recommendations

Enable AlloyDB data access audit logging and forward events to a centralized analytics platform for retention and correlation.
Alert on successful administrative logins to AlloyDB from any IP address not on an approved allowlist.
Monitor Terraform plan and apply operations that create or modify google_alloydb_cluster resources for missing or weak password attributes.
Track outbound data transfer volumes from AlloyDB instances to detect potential exfiltration following credential abuse.

How to Mitigate CVE-2026-7428

Immediate Actions Required

Rotate the administrative password on every AlloyDB cluster created via Terraform or REST API before 2025-11-03.
Restrict network access to AlloyDB clusters using authorized networks, private service connect, or VPC peering controls.
Audit Google Cloud IAM and AlloyDB audit logs for unauthorized authentication or privilege use since cluster creation.
Re-run Terraform configurations against the patched provider behavior to confirm strong credentials are enforced.

Patch Information

Google remediated the provisioning behavior on the AlloyDB service side. Clusters created after 2025-11-03 through Terraform or the REST API no longer accept the insecure default password. Refer to the Google Cloud AlloyDB release notes for the official vendor advisory and effective dates.

Workarounds

Explicitly set a high-entropy initial_user.password value when defining google_alloydb_cluster resources in Terraform.
Manage AlloyDB administrative credentials through Google Secret Manager and inject them at provisioning time rather than committing them to code.
Place AlloyDB clusters on private IP only and require connections through approved bastion hosts or workload identities.
Enforce password rotation policies and remove any legacy administrative accounts that retain the default credential.

bash

# Configuration example
# Terraform: enforce a strong password sourced from Secret Manager
resource "google_alloydb_cluster" "primary" {
  cluster_id = "prod-cluster"
  location   = "us-central1"

  initial_user {
    user     = "postgres"
    password = data.google_secret_manager_secret_version.alloydb_admin.secret_data
  }

  network_config {
    network = google_compute_network.private_vpc.id
  }
}