CVE-2026-46621 Yamcs: Authenticated Remote Code Execution (RCE) via Jython Algorithm Code Injection
Authenticated attackers can inject malicious Python code into Yamcs algorithms to execute arbitrary commands on the host system.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-46621?
CVE-2026-46621 is a critical code injection vulnerability in yamcs, published on 16 Jul 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
Yamcs is a mission control framework. Prior to 5.12.7, the Yamcs script evaluation engine for Python algorithms dynamically compiled and evaluated user-controlled algorithm text using Jython through the JSR-223 ScriptEngine API without enforcing a secure sandbox, so an authenticated user with the ChangeMissionDatabase privilege could override an existing Python algorithm's logic through the mission database REST API and import and execute arbitrary Java classes such as java.lang.Runtime to achieve remote code execution on the underlying host operating system. This issue is fixed in versions 5.12.7 and 5.13.0, which disable algorithm editing by default.
Weakness: CWE-94
Which versions are affected by CVE-2026-46621?
2 open source packages ship an affected version, including org.yamcs:yamcs-core. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
org.yamcs:yamcs-core Maven | All versions | 5.12.7 |
org.yamcs:yamcs-core Maven | All versions | 5.12.7 |
Products include Spaceapplications Yamcs.
How do I fix CVE-2026-46621?
Upgrade org.yamcs:yamcs-core to 5.12.7 or later.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-46621 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-46621 exists.
Other vulnerabilities in yamcs
- CVE-2026-46562 Yamcs: Remote Code Execution via Mission Database algorithm override
- CVE-2026-44632 Yamcs: Server-Side Code Injection (RCE) via Janino Expression Engine in `JavaExprAlgorithmExecutionFactory`
- CVE-2023-45278 Yamcs API Directory Traversal vulnerability
- CVE-2023-45277 Yamcs Path Traversal vulnerability
- CVE-2026-44596 Yamcs: No Rate Limiting on Authentication Endpoint
Sources
Also known as GHSA-2g95-6x5q-xjwj.