CVE-2026-77157 in ast-cli
Summary
by MITRE • 10/22/2026
ast-cli downloads two helper binaries, the Vorpal ASCA real-time engine and the SCA Resolver, from "download.checkmarx.com" as part of its auto-update flow, triggered by the Checkmarx’s "VSCode/JetBrains" extensions and by cx scan "sca-realtime".
Prior to the fix, the downloaded archive was not verified against a checksum before extraction and execution. An attacker able to substitute the served archive could deliver an arbitrary binary that ast-cli would extract and execute the contents of the archive, since no integrity check was performed on the download.
Successful exploitation requires compromising "download.checkmarx.com" and replacing the served archive with one containing an attacker-controlled binary. If the served archive had been replaced that way, any developer machine or CI pipeline invoking ASCA (via Checkmarx's VSCode/JetBrains extensions) or cx scan "sca-realtime" on an affected version would have extracted and executed that binary in place of the intended download.
The download is now verified against a published SHA-256 checksum before extraction.
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Analysis
by VulDB Data Team • 10/22/2026
This vulnerability represents a critical failure in supply chain security within the Checkmarx ast-cli tool, specifically affecting its auto-update mechanism for helper binaries known as the Vorpal ASCA real-time engine and the SCA Resolver. The core technical flaw lies in the absence of integrity verification during the download process from "download.checkmarx.com." When these extensions or scan commands are triggered on affected versions, the system retrieves an archive containing essential components but proceeds to extract and execute its contents without performing any checksum validation against a known good value. This design oversight creates a direct path for code injection if the distribution server is compromised or if a man-in-the-middle attacker can intercept and modify the traffic between the client and the download endpoint.
The operational impact of this vulnerability is severe, as it allows an adversary to achieve arbitrary code execution on any machine running the vulnerable ast-cli version. Successful exploitation requires that an attacker compromises "download.checkmarx.com" or successfully manipulates the network path to substitute the legitimate archive with a malicious one containing attacker-controlled binaries. Once such a substitution occurs, every developer workstation or continuous integration pipeline invoking ASCA through Checkmarx's VSCode/JetBrains extensions or executing cx scan sca-realtime commands will automatically download and execute the compromised binary under the privileges of the user running the tool. This effectively turns routine development activities into vectors for system compromise, potentially leading to data exfiltration, lateral movement within corporate networks, or persistent backdoor installation on critical build servers.
From a classification perspective, this vulnerability aligns with CWE-352 Cross-Site Request Forgery in terms of trust assumptions but is more accurately categorized under CWE-862 Missing Authorization and CWE-798 Use of Hard-coded Credentials if authentication was involved, though the primary issue here is CWE-1047 Cryptographic Failures due to the lack of integrity checks. In the context of the MITRE ATT&CK framework, this flaw facilitates techniques related to Supply Chain Compromise (T1195) and potentially Command and Scripting Interpreter execution if the injected binary leverages scripting capabilities for persistence or further exploitation. The attack vector is primarily network-based but relies on the trust placed in third-party update servers, highlighting a common weakness in software distribution models that prioritize convenience over security verification during automatic updates.
To mitigate this risk, organizations must ensure they are running patched versions of ast-cli where the download process has been updated to verify archives against published SHA-256 checksums before extraction and execution. This cryptographic validation ensures that any modification to the downloaded files by an attacker will be detected and rejected. Additionally, security teams should implement network monitoring to detect anomalous traffic patterns associated with unauthorized updates or connections to unexpected domains. It is also advisable to restrict outbound internet access for CI/CD pipelines and developer workstations where possible, allowing only verified update sources through firewalls or proxy servers that can perform additional integrity checks. Regular auditing of installed software versions against vendor advisories remains essential to maintain a secure development environment free from supply chain vulnerabilities.