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YamcsApplication · Spaceapplications

CVE-2026-46621

CRITICAL · 9.1 CVSS v3.1 Published 2026-07-16
Fix available
A fix is available. Upgrade to 5.12.7 or later.
See remediation →
97/100
Remediation priority · Urgent
Remotely reachable Zero-click 5 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Yamcs versions prior to 5.12.7 have a critical RCE vulnerability where the Jython-based script evaluation engine for Python algorithms uses the JSR-223 ScriptEngine API without a secure sandbox. An authenticated user with ChangeMissionDatabase privilege can override Python algorithm logic via the mission database REST API and import arbitrary Java classes like java.lang.Runtime to execute OS-level commands.

MitigationUpgrade to Yamcs 5.12.7 or 5.13.0, which disables algorithm editing by default. If algorithm editing is required, implement strict access controls on the ChangeMissionDatabase privilege and consider additional sandboxing measures.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
YamcsApplication
Affected:< 5.12.7

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Yamcs installation and version
    Locate the Yamcs installation directory and check the version file or startup logs. Common locations include /opt/yamcs or the directory where yamcs-server.jar resides. Run 'java -jar yamcs-server.jar --version' or check version.info if present.
    Affected if The installed version is below 5.12.7 (any 5.x version prior to 5.12.7 is affected)
  2. Verify if algorithm editing is enabled
    Check the Yamcs configuration file (typically yamcs.yaml or yamcs.properties) for algorithm-related settings. Look for parameters controlling algorithm creation/editing in the mission database configuration section.
    Affected if Algorithm editing is explicitly enabled in the configuration (the fix in 5.12.7/5.13.0 disables it by default)
  3. Audit users with ChangeMissionDatabase privilege
    Review Yamcs user accounts and role definitions. Check the authentication/authorization configuration for users assigned the 'ChangeMissionDatabase' privilege. This is typically found in the users section of the YAML configuration.
    Affected if There are users or service accounts with ChangeMissionDatabase privilege that could import and modify algorithms
  4. Inspect existing algorithm definitions
    Access the mission database through the Yamcs web interface or API. Navigate to the algorithm repository and list all defined algorithms. Look for any algorithms containing suspicious imports (such as java.lang.Runtime) or command execution patterns.
    Affected if Algorithms exist that import Java classes like java.lang.Runtime or contain shell command invocations

You are affected if your Yamcs version is below 5.12.7 AND algorithm editing is enabled AND users with ChangeMissionDatabase privilege exist in your environment.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.12.7 or later
Fixed in 5.12.7
Interim mitigation

Upgrade to Yamcs 5.12.7 or 5.13.0, which disables algorithm editing by default. If algorithm editing is required, implement strict access controls on the ChangeMissionDatabase privilege and consider additional sandboxing measures.

Recommended fix High confidence

5.12.7 or 5.13.0 (or later stable release)

  1. Upgrade Yamcs to version 5.12.7 or 5.13.0 (or latest stable version available)
  2. After upgrade, verify that algorithm editing is disabled by default as per the security fix
  3. If algorithm editing is required, explicitly enable it through configuration with appropriate security controls
  4. Review user permissions and restrict the ChangeMissionDatabase privilege to only trusted, authenticated users
  5. Audit existing Python algorithms in the mission database for any unauthorized modifications
Caveat Algorithm editing is now disabled by default, which may break existing workflows that rely on editing Python algorithms through the mission database REST API

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Yamcs Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-46621 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data