FKIE_CVE-2026-55559

Vulnerability from fkie_nvd - Published: 2026-08-28 20:18 - Updated: 2026-08-28 22:16
Severity
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs inserts templateArgs from POST /api/instances and PATCH /api/instances/{instance} into YAML through VarStatement.append in yamcs-core/src/main/java/org/yamcs/templating/VarStatement.java without YAML-context escaping. The rendered configuration is parsed by YamcsServer.createInstance and loaded by YamcsServerInstance, allowing an attacker to inject a services entry for org.yamcs.ProcessRunner. Deployments without security.yaml expose the operation through the guest superuser, while secured deployments require SystemPrivilege.CreateInstances. Successful exploitation executes commands as the Yamcs service account. This issue is fixed in versions 5.12.8 and 5.13.2.
References
security-advisories@github.comhttps://github.com/yamcs/yamcs/commit/549f295cf8c5496a5e799d6bec2432ef976c82aa
security-advisories@github.comhttps://github.com/yamcs/yamcs/commit/7192da1c49bdf5ab1d72e579a47766a7c43e87c8
security-advisories@github.comhttps://github.com/yamcs/yamcs/releases/tag/yamcs-5.12.8
security-advisories@github.comhttps://github.com/yamcs/yamcs/releases/tag/yamcs-5.13.2
security-advisories@github.comhttps://github.com/yamcs/yamcs/security/advisories/GHSA-73mf-m39p-wpm9
134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/yamcs/yamcs/security/advisories/GHSA-73mf-m39p-wpm9
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "yamcs",
          "vendor": "yamcs",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 5.12.8"
            },
            {
              "status": "affected",
              "version": "\u003e= 5.13.0, \u003c 5.13.2"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs inserts templateArgs from POST /api/instances and PATCH /api/instances/{instance} into YAML through VarStatement.append in yamcs-core/src/main/java/org/yamcs/templating/VarStatement.java without YAML-context escaping. The rendered configuration is parsed by YamcsServer.createInstance and loaded by YamcsServerInstance, allowing an attacker to inject a services entry for org.yamcs.ProcessRunner. Deployments without security.yaml expose the operation through the guest superuser, while secured deployments require SystemPrivilege.CreateInstances. Successful exploitation executes commands as the Yamcs service account. This issue is fixed in versions 5.12.8 and 5.13.2."
    }
  ],
  "id": "CVE-2026-55559",
  "lastModified": "2026-08-28T22:16:51.073",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-55559",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-08-28T19:57:53.907806Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-28T20:18:28.930",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/yamcs/yamcs/commit/549f295cf8c5496a5e799d6bec2432ef976c82aa"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/yamcs/yamcs/commit/7192da1c49bdf5ab1d72e579a47766a7c43e87c8"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/yamcs/yamcs/releases/tag/yamcs-5.12.8"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/yamcs/yamcs/releases/tag/yamcs-5.13.2"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/yamcs/yamcs/security/advisories/GHSA-73mf-m39p-wpm9"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/yamcs/yamcs/security/advisories/GHSA-73mf-m39p-wpm9"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-94"
        },
        {
          "lang": "en",
          "value": "CWE-470"
        },
        {
          "lang": "en",
          "value": "CWE-1336"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}



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