Quick answers
- Is CVE-2026-121753 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-121753 being exploited in the wild.
- How severe is CVE-2026-121753?
- 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-2026-121753?
- No fixed version is recorded yet. Restrict user interaction with XE files from untrusted sources; avoid opening XE files from suspicious or unknown origins 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-2026-121753 attacked?
- It is attacked with local access.
- Am I affected by CVE-2026-121753?
- 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 XE files from untrusted sources; avoid opening XE files from suspicious or unknown origins until a patch is available.
Technical details
A use-after-free vulnerability exists in Cobalt's XE file parser due to insufficient validation of object existence before dereferencing. An attacker can craft a malicious XE file that causes the application to operate on a freed object, leading to arbitrary code execution in the process context. User interaction is required (opening a malicious file or visiting a malicious page), and no fix has been disclosed.
Affected products
- Ashlar-Vellum Cobalt
Timeline
- 2025-12-16: disclosed: Vulnerability reported to vendor
- 2026-11-04: advisory: Coordinated public disclosure