CVE-2026-76139 in Advanced Cluster Management for Kubernetes
Summary
by MITRE • 08/20/2026
A flaw was found in acm-operator-bundle. The build process for this component downloads and runs a script from a remote source without verifying its authenticity or integrity. This script gains access to sensitive credentials, such as GitHub access tokens and registry passwords, used in the build environment. A remote attacker could exploit this vulnerability to inject malicious code, leading to unauthorized access to build resources and potential compromise of the resulting operator bundle.
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Analysis
by VulDB Data Team • 08/20/2026
The acm-operator-bundle component contains a critical supply chain security flaw rooted in insecure software construction practices. Specifically, the build process retrieves and executes scripts from untrusted remote sources without performing any form of authenticity verification or integrity checking. This architectural weakness violates fundamental principles of secure development by assuming that external inputs are benign, thereby exposing the entire compilation pipeline to manipulation. In modern continuous integration and deployment environments, such as those used for OpenShift Advanced Cluster Management operator bundles, the build environment often possesses elevated privileges and access to sensitive artifacts required for packaging and distribution. When a script is downloaded from an arbitrary remote endpoint without cryptographic validation of its source or content hash, it creates a direct vector for supply chain attacks where malicious actors can intercept or compromise the delivery mechanism to inject harmful code into the final software artifact.
The operational impact of this vulnerability is severe due to the high-privilege nature of build environments. The unverified script gains access to sensitive credentials stored within the build context, including GitHub personal access tokens and container registry passwords. These secrets are typically used to authenticate with external repositories during the fetch or push phases of the build process. If an attacker successfully injects malicious code into this script, they can exfiltrate these credentials in real-time as the build executes. This leads directly to unauthorized access to private source code repositories, allowing for further malware injection or intellectual property theft. Furthermore, because the compromised script is part of the bundle generation process, it may also alter the resulting operator bundle itself, embedding backdoors or malicious logic that persists when the operator is deployed in production clusters, thereby compromising downstream systems and data confidentiality.
From a classification perspective, this vulnerability aligns with CWE-829, which describes Inclusion of Functionality from Untrusted Control Sphere, as well as CWE-502, Deserialization of Untrusted Data if the script execution involves parsing unverified inputs. The attack vector is consistent with MITRE ATT&CK technique T1195.002, Supply Chain: Compromise Software Supply Chain, where adversaries target third-party software components to gain initial access or persistence. Additionally, the exfiltration of credentials falls under T1534, Internal Spearphishing, if used for lateral movement, but more accurately maps to T1078, Valid Accounts, as stolen tokens provide legitimate-looking authentication to external services. The lack of integrity verification also relates to CWE-345, Insufficient Verification of Data Authenticity, highlighting the failure to ensure that executed code matches its expected origin and content.
To mitigate this vulnerability, immediate remediation requires implementing strict supply chain security controls within the build pipeline. Developers must replace direct script downloads with verified artifact retrieval methods, such as using signed packages or checksums validated against a trusted manifest before execution. Implementing Content Security Policy (CSP) headers for any web-based components and enforcing allow-lists for remote resources can prevent unauthorized code execution. Additionally, secrets management best practices should be adopted, ensuring that credentials are injected via secure vaults like HashiCorp Vault or Kubernetes Secrets with restricted access scopes rather than being exposed as environment variables to the build script. Regular auditing of third-party dependencies and adopting software bill of materials (SBOM) standards can further enhance visibility into the components included in the operator bundle, reducing the risk of future supply chain compromises.