CVE-2026-15793 in BuildKit
Summary
by MITRE • 07/21/2026
BuildKit custom frontends or clients using the raw low-level API can set git.checkoutbundle=true when checking out Git sources. If the Git source is malicious, this could lead to a crafted command invocation on the host.
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Analysis
by VulDB Data Team • 07/21/2026
This vulnerability exists within BuildKit's implementation of Git source handling where custom frontends or clients can explicitly enable the git.checkoutbundle=true configuration option during repository checkout operations. The flaw stems from an insufficient input validation mechanism that allows arbitrary command execution through crafted Git repositories when this specific flag is activated.
The technical implementation involves BuildKit's low-level API interface which permits direct manipulation of Git checkout parameters without adequate sanitization of repository contents. When git.checkoutbundle=true is set, the system attempts to process Git bundle files with enhanced functionality that includes executing shell commands embedded within the repository metadata or configuration files. This creates an execution path where malicious actors can craft specially constructed Git repositories containing harmful command sequences that get executed in the context of the BuildKit host environment.
The operational impact of this vulnerability extends beyond typical code execution scenarios as it provides attackers with potential access to the underlying build infrastructure. The vulnerability maps directly to CWE-78 which describes improper neutralization of special elements used in OS commands, and aligns with ATT&CK technique T1059.001 for command and scripting interpreter. An attacker could leverage this weakness to execute arbitrary code on the build host, potentially gaining access to sensitive build artifacts, credentials stored in environment variables, or other resources accessible to the build process.
The attack surface is particularly concerning when considering that BuildKit is commonly used in CI/CD pipelines and container image building scenarios where trust assumptions may be relaxed. The vulnerability affects systems where custom frontends are employed, making it more prevalent in enterprise environments that utilize proprietary build tools rather than standard Docker CLI operations. Even when using the default client, certain advanced configuration options or third-party integrations might inadvertently enable this risky behavior.
Mitigation strategies should focus on implementing strict input validation for Git repository contents and disabling potentially dangerous checkout bundle features by default. Organizations should enforce principle of least privilege for build environments, limit access to trusted repositories, and implement network segmentation to reduce the potential impact of successful exploitation. The recommended approach includes configuring BuildKit with explicit security boundaries that prevent automatic execution of commands from untrusted sources, along with regular auditing of build configurations to ensure that git.checkoutbundle=true is not inadvertently enabled in production environments. Additionally, implementing container runtime security controls and monitoring for suspicious command execution patterns can provide defense-in-depth protection against exploitation attempts.