CVE-2026-121742 Ashlar-Vellum Cobalt XE File Parsing Use-After-Free Remote Code Execution Vulnerability
A malicious XE file opened in Ashlar-Vellum Cobalt can trigger a use-after-free and execute code; Cobalt users should care.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Harmful if only installed
- No
- Needs a specific call
- No
- Fix
- None listed
What is CVE-2026-121742?
CVE-2026-121742 is a high-severity use after free vulnerability in Ashlar-Vellum Cobalt, published on 12 Nov 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
Ashlar-Vellum Cobalt XE File Parsing Use-After-Free 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 XE files. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-28757.
Weakness: CWE-416
Which versions are affected by CVE-2026-121742?
An affected version is exposed as installed. No special setting or call is needed.
How do I fix CVE-2026-121742?
No fix has been published for CVE-2026-121742 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-121742 being exploited?
There is no known exploitation of CVE-2026-121742 in the wild and no public exploit code.
Sources
Also known as GHSA-hxcm-3w52-5fpx.