CVE-2026-19781: Ashlar-Vellum Cobalt VS File Parsing Heap-based Buffer Overflow Remote Code Execution Vulnerability
Ashlar-Vellum Cobalt VS File Parsing Heap-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Ashlar-Vellum Cobalt. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
The specific flaw exists within the parsing of VS files. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a heap-based buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-28173.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Patch ZDI-CAN-28173 - Compensating control
Mitigate exploitability by preventing users from opening malicious VS files (e.g., block or quarantine .vs file delivery via email/web filtering and restrict where these files can be opened).
Event History
Frequently Asked Questions
Does exploitation require an attacker to have an account or other privileges on the target system?
No attacker privileges are required. However, exploitation requires user interaction: the target must visit a malicious page or open a malicious file.
What level of access could successful exploitation provide?
An attacker can execute arbitrary code in the context of the current Ashlar-Vellum Cobalt process. The vulnerability is rated high severity with impacts to confidentiality, integrity, and availability.