{"id":"CVE-2026-55559","title":"Yamcs is a mission control framework","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/templat…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-94","CWE-470","CWE-1336"],"vendor":"yamcs","product":"org.yamcs:yamcs-core","affected":["org.yamcs:yamcs-core >= 5.13.0, <= 5.13.1","org.yamcs:yamcs-core <= 5.12.7"],"patched":["org.yamcs:yamcs-core 5.13.2","org.yamcs:yamcs-core 5.12.8"],"published":"2026-08-28","updated":"2026-09-08","sourceUpdated":"2026-09-08T21:08:37.320","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-55559","references":[{"url":"https://github.com/yamcs/yamcs/commit/549f295cf8c5496a5e799d6bec2432ef976c82aa","label":"security-advisories@github.com"},{"url":"https://github.com/yamcs/yamcs/commit/7192da1c49bdf5ab1d72e579a47766a7c43e87c8","label":"security-advisories@github.com"},{"url":"https://github.com/yamcs/yamcs/releases/tag/yamcs-5.12.8","label":"security-advisories@github.com"},{"url":"https://github.com/yamcs/yamcs/releases/tag/yamcs-5.13.2","label":"security-advisories@github.com"},{"url":"https://github.com/yamcs/yamcs/security/advisories/GHSA-73mf-m39p-wpm9","label":"security-advisories@github.com"},{"url":"https://github.com/yamcs/yamcs/security/advisories/GHSA-73mf-m39p-wpm9","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://github.com/advisories/GHSA-73mf-m39p-wpm9"}],"tags":["nvd","ghsa","maven"],"epss":0.00552,"epssPercentile":0.45022,"aliases":["GHSA-73mf-m39p-wpm9"],"ecosystem":"maven","ingestedAt":"2026-08-28T18:23:38.006Z","slug":"CVE-2026-55559","body":"## Overview\n\nYamcs 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Package advisory (CVE-2026-55559)\n\nAffected packages:\n\n- `org.yamcs:yamcs-core >= 5.13.0, <= 5.13.1`\n- `org.yamcs:yamcs-core <= 5.12.7`\n\nPatched in:\n\n- `org.yamcs:yamcs-core 5.13.2`\n- `org.yamcs:yamcs-core 5.12.8`\n\nSource: https://github.com/advisories/GHSA-73mf-m39p-wpm9","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}