CVE-2026-93326 in BuildKit
Summary
by MITRE • 10/06/2026
A build step for a Git source, crafted in a specific way, can bypass some policy validation rules. A malicious build definition can make the repository look like it is coming from a different remote URL than it really is when Git clone is happening. If policy is doing more stricter validation, for example based on commit SHA, commit data, or signatures, then all these validations still apply correctly.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 10/06/2026
The vulnerability described involves a flaw in the build system's handling of Git source repositories, specifically within the context of automated CI/CD pipelines where policy enforcement is critical for security and compliance. This issue arises when a malicious actor constructs a specific type of build definition that manipulates how the underlying Git client interprets the remote URL during the cloning process. By exploiting this behavior, an attacker can make it appear to the system's validation logic that the repository originates from a trusted or expected remote URL, while in reality, the code is being fetched from a different, potentially malicious source. This technique effectively bypasses certain policy rules that rely on superficial checks of the remote origin string rather than deeper cryptographic verification of the content itself.
From a technical perspective, this flaw leverages ambiguities or inconsistencies in how Git resolves repository sources during initialization phases. When a build step is configured to pull from a specific URL, standard validation mechanisms often inspect the initial connection parameters to ensure they match predefined allowlists or trusted domains. However, if the implementation does not strictly enforce canonicalization of URLs or fails to verify that the final resolved state matches the declared intent before proceeding with further operations, an attacker can inject configurations that redirect the clone operation without triggering these surface-level alerts. The core issue lies in the disconnect between the perceived source identity and the actual data origin during the critical initialization window where policies are evaluated.
The operational impact of this vulnerability is significant for organizations relying on automated policy enforcement to maintain supply chain integrity. If an attacker successfully exploits this bypass, they can introduce malicious code into a build pipeline that appears legitimate according to initial checks. This could lead to the deployment of compromised software artifacts, injection of backdoors, or exfiltration of sensitive data during subsequent stages of the CI/CD process. The risk is particularly acute in environments where trust is established primarily through URL whitelisting rather than comprehensive cryptographic verification. Such an attack undermines the principle of least privilege and can lead to widespread compromise if the malicious build artifacts are propagated downstream to production systems or shared with other teams.
Despite this bypass capability, the vulnerability has limitations that mitigate its severity under strict security configurations. As noted in the description, more rigorous validation methods remain effective against such attacks. Specifically, policies based on commit SHA-1 hashes, detailed commit metadata analysis, and cryptographic signature verification are not affected by URL manipulation techniques. These deeper inspection mechanisms verify the actual content of the repository rather than just its declared source address. Therefore, organizations that enforce strict integrity checks using signed commits or pinned SHAs can largely neutralize this threat vector because the malicious code would fail to match the expected cryptographic fingerprints regardless of how it was fetched.
To mitigate this risk, security teams should prioritize implementing defense-in-depth strategies within their CI/CD pipelines. It is essential to move beyond simple URL-based allowlists and adopt stricter validation criteria that include verifying commit signatures using tools like GPG or SSH keys. Additionally, enforcing pinned versions by SHA-1 hash ensures that even if the source repository is compromised or redirected, the build process will reject any code that does not match the exact expected state. Regular audits of build definitions should also be conducted to detect unusual configurations that might attempt to exploit URL resolution ambiguities. Aligning these practices with industry standards such as CWE-20 for Improper Input Validation and ATT&CK techniques related to supply chain compromise can further strengthen the security posture against such sophisticated bypass attempts.