CVE-2026-112407: AWS CICD Toolchain Privilege Escalation

CVE-2026-112407 Overview

CVE-2026-112407 is an incorrect privilege assignment vulnerability [CWE-266] in the Identity and Access Management (IAM) policy of the AWS CICD-toolchain-for-serverless-applications, versions 1.0.7 through 1.0.10. The flaw allows remote authenticated users with push access to the application source repository to escalate privileges within the same AWS account. Attackers can abuse the toolchain pipeline to deploy application templates that access or modify resources outside the intended application stack. AWS addressed the issue in version 1.0.11.

Critical Impact

Authenticated users with repository push access can escalate privileges and compromise AWS account resources beyond the application stack boundary.

Affected Products

• AWS CICD-toolchain-for-serverless-applications 1.0.7
• AWS CICD-toolchain-for-serverless-applications 1.0.8 through 1.0.9
• AWS CICD-toolchain-for-serverless-applications 1.0.10

Discovery Timeline

• 2026-10-20 - CVE-2026-112407 published to NVD
• 2026-10-22 - Last updated in NVD database

Technical Details for CVE-2026-112407

Vulnerability Analysis

The AWS CICD-toolchain-for-serverless-applications provisions a Continuous Integration and Continuous Delivery (CI/CD) pipeline for building and deploying serverless workloads. The pipeline executes application templates with an IAM role whose permissions exceed the scope of a single application stack. An attacker with push access to the source repository can modify or introduce application templates that leverage the over-privileged pipeline role. The pipeline then deploys those templates, enabling the attacker to reach resources elsewhere in the AWS account.

Root Cause

The root cause is incorrect privilege assignment in the IAM policy attached to the toolchain pipeline. The policy grants permissions broader than those required to manage the application stack itself. Because the policy is not scoped to the stack's own resources, templates deployed through the pipeline inherit account-wide capabilities. This violates the principle of least privilege for infrastructure-as-code pipelines.

Attack Vector

Exploitation requires network access and authenticated push rights to the source repository that feeds the toolchain. The attacker commits a modified AWS CloudFormation or Serverless Application Model (SAM) template that references resources outside the application stack. On the next pipeline run, the toolchain's privileged role deploys the template, resulting in unauthorized read or write access to other AWS resources. No user interaction beyond the normal pipeline trigger is required.

The vulnerability is described in the AWS Security Bulletin 2026-141 and the GitHub Security Advisory GHSA-f76m-4xrx-pvq5.

Detection Methods for CVE-2026-112407

Indicators of Compromise

• Unexpected CloudFormation or SAM template changes in the source repository that reference resources outside the declared application stack.
• AWS CloudTrail events from the toolchain pipeline role touching resources that do not belong to the application stack.
• New or modified IAM roles, policies, S3 buckets, or Lambda functions created by the pipeline execution role outside its usual naming scope.

Detection Strategies

• Audit the trust policy and permissions of the pipeline's deployment role for resource-level scoping and condition keys.
• Diff application templates against known-good baselines before each pipeline run to flag out-of-scope resource references.
• Correlate repository push events with downstream CloudTrail activity to identify commits that trigger abnormal resource access.

Monitoring Recommendations

• Enable CloudTrail organization trails and forward events into a centralized data lake for cross-account correlation.
• Alert on iam:PassRole, cloudformation:CreateStack, and cloudformation:UpdateStack calls initiated by the toolchain role against unexpected targets.
• Monitor repository access logs for new committers or unusual push patterns against branches wired to the pipeline.

How to Mitigate CVE-2026-112407

Immediate Actions Required

• Upgrade all existing toolchain stacks to version 1.0.11 or later as directed by the vendor.
• Review the IAM policies attached to the toolchain pipeline role and remove permissions that fall outside the application stack scope.
• Rotate any credentials or secrets managed by stacks previously deployed through vulnerable toolchain versions.

Patch Information

AWS released the fix in GitHub Release v1.0.11. Users of versions 1.0.7 through 1.0.10 must redeploy the toolchain stack with the patched version. Refer to the AWS Security Bulletin 2026-141 for authoritative remediation guidance.

Workarounds

• Restrict repository push access to a minimal set of trusted maintainers and require pull-request review before merges to pipeline-tracked branches.
• Add CloudFormation stack policies and permission boundaries that constrain the deployment role to resources tagged for the application stack.
• Enable manual approval stages in the pipeline for template changes until the toolchain is upgraded to 1.0.11.