# CVE-2026-121744: Ashlar-Vellum Cobalt stack-based buffer overflow in XE file parsing

Source: https://junglewise.ai/threats/cve-2026-121744-ashlar-vellum-cobalt-xe-file-parsing-stack-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-2026-121744 · Severity: high · CVSS 7.8 · Published 2026-11-12

Ashlar-Vellum Cobalt is a design and engineering software used for technical drawings and modeling. A stack-based buffer overflow in the XE file parser allows attackers to execute arbitrary code when a user opens a malicious file or visits a malicious page. This could enable complete system compromise and data theft.

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-2026-121744 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-121744 being exploited in the wild.

**How severe is CVE-2026-121744?** 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-2026-121744?** No fixed version is recorded yet. Restrict user interaction with untrusted XE 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-2026-121744 attacked?** It is attacked with local access.

**Am I affected by CVE-2026-121744?** 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 XE files and avoid opening files from untrusted sources until a patch is available.

## Technical details

The vulnerability is a stack-based buffer overflow in Cobalt's XE file parsing routine, caused by insufficient validation of user-supplied data length before copying to a stack buffer. User interaction is required—the target must open a malicious XE file or visit a malicious page triggering file download. An attacker gains arbitrary code execution in the context of the Cobalt process.

## Affected products

- Ashlar-Vellum Cobalt

## Timeline

- 2025-11-11: disclosed
- 2026-11-04: advisory

## References

- [https://www.zerodayinitiative.com/advisories/ZDI-26-870/](https://www.zerodayinitiative.com/advisories/ZDI-26-870/)

## 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 heap buffer overflow in LI file parsing](https://junglewise.ai/threats/cve-2026-121752-ashlar-vellum-cobalt-li-file-parsing-heap-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)