CVE-2026-19759: Google Cloud Application Integration Auth Bypass

CVE-2026-19759 Overview

CVE-2026-19759 is an Incorrect Authorization vulnerability [CWE-863] in the task configuration of Google Cloud Application Integration. The flaw affects versions prior to the 2026-06-17 release on Google Cloud Platform. An authenticated Google Cloud user can leverage an internal-only task type to execute arbitrary internal Remote Procedure Calls (RPCs) from inside Google's production network under a privileged identity. Google patched the issue on 17 June 2026 and states that no customer action is required.

Critical Impact

Authenticated attackers can issue internal RPCs under a privileged service identity, breaching the trust boundary between tenant workloads and Google's production control plane.

Affected Products

• Google Cloud Application Integration (versions prior to the 2026-06-17 release)
• Google Cloud Platform tenants that configured Application Integration tasks
• Workflows depending on Application Integration task execution

Discovery Timeline

• 2026-06-17 - Google Cloud releases the Application Integration patch
• 2026-09-28 - CVE-2026-19759 published to the National Vulnerability Database (NVD)
• 2026-09-29 - Last updated in NVD database

Technical Details for CVE-2026-19759

Vulnerability Analysis

The vulnerability resides in how Google Cloud Application Integration validated task configurations submitted by authenticated tenants. The service exposes task types that are intended for internal Google use only, but the authorization layer did not restrict external callers from selecting these task types. By configuring an internal-only task, an authenticated Google Cloud user caused the Application Integration backend to execute arbitrary internal RPCs on their behalf.

These RPCs ran under a privileged service identity located inside Google's production network. That identity carries far broader access than any tenant principal, enabling cross-tenant data exposure and lateral movement within the control plane. The Common Weakness Enumeration category CWE-863 (Incorrect Authorization) captures the mismatch between the policy that should have governed internal task types and what the service actually enforced.

Root Cause

The root cause is missing authorization enforcement on the task type field inside the task configuration API. The service treated the caller's authentication as sufficient and did not validate whether the chosen task type was permitted for external tenants. Internal-only tasks therefore became reachable from the public API surface.

Attack Vector

Exploitation requires only a low-privileged, authenticated Google Cloud identity with access to Application Integration. The attacker submits a task configuration that references an internal-only task type and triggers execution. The Application Integration runtime then invokes the targeted internal RPC from within Google's production network, using a privileged identity rather than the caller's identity. No user interaction is required.

No verified public proof-of-concept exists. See the Google Cloud Security Bulletin for the vendor description.

Detection Methods for CVE-2026-19759

Indicators of Compromise

• Application Integration task configurations that reference undocumented or internal-only task types.
• Audit log entries showing task executions that invoke RPC targets outside the tenant's project boundary.
• Unexpected successful calls originating from Application Integration service identities against sensitive Google Cloud APIs.

Detection Strategies

• Review Cloud Audit Logs for integrations.googleapis.com activity and flag task creations or updates that specify non-standard task type identifiers.
• Correlate task execution events with downstream API calls to detect privilege escalation patterns across projects.
• Baseline normal task-type usage per project and alert on deviations introduced before the 17 June 2026 patch date.

Monitoring Recommendations

• Stream Google Cloud audit and Application Integration logs into a centralized analytics platform for continuous review.
• Monitor Identity and Access Management (IAM) changes granting Application Integration roles to new principals.
• Track service identity usage patterns to detect anomalous RPC targets or unusual request volumes.

How to Mitigate CVE-2026-19759

Immediate Actions Required

• Confirm the environment is running the post-2026-06-17 Application Integration release; Google applied the fix on the managed service, so no tenant upgrade is required.
• Audit existing Application Integration task configurations for unexpected task type values and remove any that cannot be attributed to a known workflow owner.
• Review IAM bindings on Application Integration to enforce least privilege for users who can create or modify integrations.

Patch Information

Google Cloud deployed the fix to Application Integration on 17 June 2026. According to the Google Cloud Security Bulletin and the Google Cloud Support Bulletin, no customer action is needed because the vulnerable code path was remediated in the managed service.

Workarounds

• No workaround is required; the vendor patched the managed service directly on 17 June 2026.
• As defense in depth, restrict roles/integrations.editor and equivalent permissions to a minimal set of trusted principals.
• Enable VPC Service Controls around sensitive projects to limit the blast radius of any future Application Integration authorization gap.

# Review IAM bindings on Application Integration for a given project
gcloud projects get-iam-policy PROJECT_ID \
  --flatten="bindings[].members" \
  --format="table(bindings.role, bindings.members)" \
  --filter="bindings.role:integrations"