Ashlar-Vellum Cobalt VS File Parsing Heap-based Buffer Overflow Remote Code Execution Vulnerability

August 24th, 2026
ZDI-26-587 ZDI-CAN-28173

CVE ID

CVE-2026-19781

CVSS Score

7.8 AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected Vendors

Ashlar-Vellum

Affected Products

Cobalt

Vulnerability Details

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.

Additional Details

Fixed in version 12.6.1204.210


Disclosure Timeline

  • 2025-11-11 - Vulnerability reported to vendor
  • 2026-08-24 - Coordinated public release of advisory
  • 2026-08-24 - Advisory Updated

Credit

Rocco Calvi (@TecR0c) with TecSecurity

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