CVE-2025-36852 is a critical security vulnerability affecting the Azure Based Remote Cache Plugin for Nx, developed by Niklas Portmann. This plugin is used in build systems that leverage bucket-based remote caching solutions such as Amazon S3 or Google Cloud Storage to speed up builds by reusing previously built artifacts. The vulnerability arises from a fundamental design flaw in the caching mechanism, specifically the "first-to-cache wins" principle. In this model, the first artifact cached for a given build input is reused for subsequent builds, regardless of the trustworthiness of the environment where it was produced. This flaw allows any contributor with pull request privileges—typically developers who can submit code changes for review—to inject malicious or compromised artifacts into the cache from untrusted environments such as feature branches or pull requests. These poisoned artifacts can then be used by trusted environments, including protected branches or production deployments, effectively bypassing all traditional security controls. The attack circumvents encryption, access controls, and checksum validation because the compromise occurs during the artifact construction phase, prior to any security verification. The vulnerability is classified under CWE-829 (Inclusion of Functionality from Untrusted Control Sphere), indicating that untrusted inputs influence critical functionality. The CVSS 4.0 score of 9.4 (critical) reflects the high impact on confidentiality, integrity, and availability, with network attack vector, low attack complexity, no user interaction, and partial authentication required (pull request privileges). No known exploits are currently reported in the wild, but the severity and ease of exploitation make this a significant threat to organizations relying on this plugin for their build and deployment pipelines.

For European organizations, this vulnerability poses a severe risk to software supply chain integrity and trustworthiness. Organizations using Nx with the Azure Based Remote Cache Plugin in their CI/CD pipelines may unknowingly deploy compromised artifacts into production, leading to potential data breaches, unauthorized code execution, or service disruptions. The ability for contributors with pull request access to inject malicious code undermines the trust model of code review and build verification processes. This could result in widespread compromise of critical applications, intellectual property theft, or introduction of backdoors and malware. Given the reliance on cloud storage services like Amazon S3 and Google Cloud Storage, which are widely used across Europe, the attack surface is broad. The vulnerability could also impact compliance with European data protection regulations (e.g., GDPR) if sensitive data is exposed or manipulated. Additionally, the disruption of production environments could affect business continuity and damage organizational reputation. The threat is particularly acute for sectors with stringent security requirements such as finance, healthcare, and critical infrastructure, where build integrity is paramount.

To mitigate this vulnerability, European organizations should implement the following specific measures: 1) Disable or avoid using the Azure Based Remote Cache Plugin for Nx until a vendor patch or secure update is available. 2) Enforce strict branch protections and limit pull request privileges to trusted personnel only, minimizing the risk of malicious artifact injection. 3) Introduce artifact signing and verification mechanisms that validate the provenance of build outputs before caching or deployment, ensuring only artifacts built in trusted environments are accepted. 4) Implement separate caches for untrusted (feature branches, pull requests) and trusted (protected branches, production) environments to prevent cross-contamination. 5) Employ continuous monitoring and auditing of build artifacts and cache contents to detect anomalies or unexpected changes. 6) Integrate additional security controls such as reproducible builds and deterministic artifact generation to reduce the risk of tampering. 7) Collaborate with the plugin vendor and community to track patch releases and apply updates promptly. 8) Consider alternative remote caching solutions with stronger security guarantees or design build pipelines that do not rely on shared caches across trust boundaries. These mitigations go beyond generic advice by focusing on architectural changes and process controls tailored to the specific flaw in the caching mechanism.