# CVE-2026-121752: Ashlar-Vellum Cobalt heap buffer overflow in LI file parsing

Source: https://junglewise.ai/threats/cve-2026-121752-ashlar-vellum-cobalt-li-file-parsing-heap-based-buffer-overflow  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-12. Updated: 2026-11-12  
License: CC BY 4.0 with a link back

CVE-2026-121752 · Severity: high · CVSS 7.8 · Published 2026-11-12

Ashlar-Vellum Cobalt is a computer-aided design and 3D modeling software used by engineers and architects. A heap buffer overflow vulnerability in its LI file parser allows remote attackers to execute arbitrary code on affected systems if a user opens a malicious file or visits a malicious page. Exploitation requires user interaction, making this a significant risk for organizations whose employees use this design software.

Technologies: [Ashlar-Vellum Cobalt](https://junglewise.ai/threats/technologies/ashlar-vellum-cobalt). Vendors: [Ashlar-Vellum](https://junglewise.ai/threats/vendors/ashlar-vellum).

## Quick answers

**Is CVE-2026-121752 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-121752 being exploited in the wild.

**How severe is CVE-2026-121752?** High severity, with a CVSS score of 7.8, published 12 November 2026.

**Which products and versions are affected?** Ashlar-Vellum Cobalt.

**Is there a fix for CVE-2026-121752?** No fixed version is recorded yet. Restrict user interaction with untrusted LI files and avoid opening files from untrusted sources until a patch is available. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-121752 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-121752?** Check whether you run Ashlar-Vellum Cobalt. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix


Restrict user interaction with untrusted LI files and avoid opening files from untrusted sources until a patch is available.

## Technical details

The vulnerability exists in the LI file parsing routine of Ashlar-Vellum Cobalt, where insufficient validation of user-supplied data length prior to copying to a heap-based buffer enables a heap-based buffer overflow. The flaw can be triggered remotely through a specially crafted LI file, allowing an attacker to execute arbitrary code in the process context. User interaction (opening a malicious file or visiting a malicious page) is required for exploitation.

## Affected products

- Ashlar-Vellum Cobalt

## Timeline

- 2025-12-04: disclosed
- 2026-11-04: advisory
- 2026-11-12: other: Published to NVD

## References

- [https://www.zerodayinitiative.com/advisories/ZDI-26-871/](https://www.zerodayinitiative.com/advisories/ZDI-26-871/)

## Related threats

- [Ashlar-Vellum Cobalt XE file parsing use-after-free remote code execution](https://junglewise.ai/threats/cve-2026-121753-ashlar-vellum-cobalt-xe-file-parsing-use-after-free-remote-code)
- [Ashlar-Vellum Cobalt stack-based buffer overflow in XE file parsing](https://junglewise.ai/threats/cve-2026-121744-ashlar-vellum-cobalt-xe-file-parsing-stack-based-buffer-overflow)
- [Ashlar-Vellum Cobalt heap-based buffer overflow in AR file parsing](https://junglewise.ai/threats/cve-2026-121743-ashlar-vellum-cobalt-ar-file-parsing-heap-based-buffer-overflow)
- [Ashlar-Vellum Cobalt use-after-free in XE file parsing](https://junglewise.ai/threats/cve-2026-121742-ashlar-vellum-cobalt-xe-file-parsing-use-after-free-remote-code)