CVE-2026-28207 Zen-C Vulnerable to Command Injection via Malicious Output Filename
Local attackers can execute arbitrary shell commands via crafted output filenames in the Zen C compiler due to unsafe system() usage.
- 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
- Fix
- None listed
What is CVE-2026-28207?
CVE-2026-28207 is a medium-severity command injection vulnerability in z-libs Zen-C, published on 26 Feb 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
Zen C is a systems programming language that compiles to human-readable GNU C/C11. Prior to version 0.4.2, a command injection vulnerability (CWE-78) in the Zen C compiler allows local attackers to execute arbitrary shell commands by providing a specially crafted output filename via the `-o` command-line argument. The vulnerability existed in the `main` application logic (specifically in `src/main.c`), where the compiler constructed a shell command string to invoke the backend C compiler. This command string was built by concatenating various arguments, including the user-controlled output filename, and was subsequently executed using the `system()` function. Because `system()` invokes a shell to parse and execute the command, shell metacharacters within the output filename were interpreted by the shell, leading to arbitrary command execution. An attacker who can influence the command-line arguments passed to the `zc` compiler (like through a build script or a CI/CD pipeline configuration) can execute arbitrary commands with the privileges of the user running the compiler. The vulnerability has been fixed in version 0.4.2 by removing `system()` calls, implementing `ArgList`, and internal argument handling. Users are advised to update to Zen C version v0.4.2 or later.
Weakness: CWE-78
Which versions are affected by CVE-2026-28207?
It affects 1 product.
Products include Zenc-Lang Zen C.
How do I fix CVE-2026-28207?
No fix has been published for CVE-2026-28207 yet. Limit exposure of the affected software until one is available.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2026-28207 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-28207 exists.
Other vulnerabilities in z-libs Zen-C
Sources
Also known as GHSA-9rff-x96h-76h2.