CVE-2026-47191 in kas
Summary
by MITRE • 08/14/2026
kas is a setup tool for bitbake based projects. Prior to version 5.3, when relying solely on a git commit ID (SHA-1 or SHA-256) to qualify if a checkout of a repository is equivalent to the state validated while adding its commit ID to a kas configuration, users may be tricked to check out a branch of the same name from this repository. This implies that the referenced repository has been taken over by an attacker and modified to carry such a branch. SHA-1 commits may also be replaced by creating hash collisions, so the primary impact of this issue is on SHA-256 commit IDs. Version 5.3 fixes the issue. As a workaround, avoid relying solely on the commit ID for integrity validation of a repository that might become under control of a malicious 3rd party. If available, additional validate cryptographically signed commits or tags. Alternatively, mirror the repository to a save place, validate its integrity, and use this instead of the original one.
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Analysis
by VulDB Data Team • 08/14/2026
The kas tool serves as a critical setup utility for bitbake-based projects, managing repository checkouts and configuration validation through commit ID references. This vulnerability affects versions prior to 5.3 where the system's integrity verification process becomes fundamentally flawed when relying exclusively on git commit IDs for repository state validation. The flaw creates a potential attack vector where malicious actors could compromise repositories by creating branches with identical names to legitimate commit IDs, effectively bypassing the intended security checks that should prevent unauthorized modifications.
The technical implementation of this vulnerability stems from insufficient validation mechanisms within kas's repository handling logic. When users specify only a commit ID without additional verification measures, the system may inadvertently check out a branch rather than the specific commit, particularly when the repository has been compromised by an attacker who creates a malicious branch with the same name as the target commit. This behavior represents a classic case of insecure dependency management and inadequate input validation in version control systems.
The operational impact extends beyond simple repository compromise to potentially enable supply chain attacks against build environments that depend on kas for project setup. Attackers could manipulate the git repository structure to redirect checkouts, introducing malicious code or modifications that bypass security controls designed to validate commit integrity. This vulnerability particularly affects SHA-256 commit IDs since SHA-1 collisions have already been demonstrated as a significant concern in cryptographic systems, making SHA-256 reliance more dangerous when proper validation mechanisms are absent.
This issue aligns with CWE-290 authentication bypass vulnerabilities and represents a failure in secure coding practices related to cryptographic verification and repository integrity checks. The vulnerability also maps to ATT&CK technique T1583.002 for developing capabilities through supply chain compromise, as attackers can exploit this weakness to modify build environments without detection. The root cause reflects poor adherence to the principle of least privilege and inadequate input sanitization in dependency management systems.
Version 5.3 addresses this vulnerability through enhanced validation mechanisms that properly distinguish between commit IDs and branch references, ensuring that specified commit IDs are strictly validated against the intended repository state rather than allowing ambiguous checkout behaviors. The recommended mitigations include implementing cryptographic signature validation for commits and tags, which aligns with industry best practices for secure software supply chain management as outlined in NIST SP 800-161 and ISO/IEC 27036 standards.
Alternative security approaches involve maintaining mirrored repositories with verified integrity checks before utilization, creating a trusted baseline that eliminates the risk of repository takeover attacks. This defensive strategy reduces reliance on external repository integrity and provides an additional layer of protection against malicious modifications. Organizations should also consider implementing automated verification processes that cross-reference commit IDs against multiple sources and maintain audit trails for all repository interactions to detect potential compromises early in the development cycle.
The vulnerability demonstrates the critical importance of proper cryptographic validation in build systems and highlights how seemingly minor implementation flaws can create significant security risks. It reinforces the need for comprehensive security testing of infrastructure tools that handle dependency management, particularly those used in critical supply chain components where integrity verification is paramount to maintaining system security posture and preventing unauthorized code injection attacks.