AWS CICD Toolchain EUVD-2026-105360

Exploitation requires the attacker to hold push access to the application source repository consumed by the CICD-toolchain-for-serverless-applications pipeline, on toolchain stack versions 1.0.7 through 1.0.10. The core precondition is the unscoped CloudFormation deployment role: because its IAM role-policy, Secrets Manager, and SSM Parameter Store write permissions were not constrained to the application's own resources, an application template deployed by the pipeline can act on other resources in the same AWS account. Limiting factors: the attacker must already be an authenticated repository contributor with write/push rights (CVSS PR:L), exploitation flows only through templates the toolchain actually deploys, and upgrading the toolchain stack to 1.0.11 or later (which adds a permissions-boundary condition and resource-scoping) closes the path.

This is a genuine but conditionally-gated privilege-escalation issue (CWE-266, Incorrect Privilege Assignment) rated CVSS 4.0 8.7 (High). The vendor-supplied CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N) indicates network reach, low attack complexity, and low-but-nonzero privileges (PR:L) - consistent with the description's requirement that the attacker already hold push access to the application source repository. High confidentiality, integrity, and availability impact on the vulnerable system is offset by SC:N/SI:N/SA:N, meaning the scoring treats the blast radius as contained to the toolchain's own authorization context even though the practical effect is reaching other resources in the same AWS account. No EPSS score was provided, there is no CISA KEV listing, and no public exploit was identified in the supplied data, so this is a high-severity-by-impact issue rather than a demonstrated mass-exploitation threat. The realistic risk is that of a trusted-insider or compromised-developer-credential scenario: the overly-broad CloudFormation deployment role is the root cause, so exposure is bounded to organizations actually running the affected toolchain versions with external or semi-trusted repository contributors. Prioritize patching where the toolchain is in active CI/CD use, but this is not an internet-facing unauthenticated emergency.

An attacker with push access to the application source repository (e.g., a lower-trust developer or a contributor whose credentials were phished) commits a malicious CloudFormation/application template that the toolchain pipeline then deploys using its over-privileged CloudFormation deployment role. Because that role is not scoped to the application's own resources, the deployed template can create or modify IAM role policies, Secrets Manager secrets, or SSM parameters elsewhere in the same AWS account, escalating privileges beyond the application stack. No public exploit code was identified in the provided data, but the attack is straightforward for anyone already holding repository push access.