{"cve":"CVE-2026-55559","nvd":{"published":"2026-08-28T20:18:28.930","modified":"2026-09-08T21:08:37.320","status":"Awaiting Analysis","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":["CWE-94","CWE-470","CWE-1336"],"references":["https://github.com/yamcs/yamcs/commit/549f295cf8c5496a5e799d6bec2432ef976c82aa","https://github.com/yamcs/yamcs/commit/7192da1c49bdf5ab1d72e579a47766a7c43e87c8","https://github.com/yamcs/yamcs/releases/tag/yamcs-5.12.8","https://github.com/yamcs/yamcs/releases/tag/yamcs-5.13.2","https://github.com/yamcs/yamcs/security/advisories/GHSA-73mf-m39p-wpm9"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:50:50.842544443+00:00"},"epss":{"cve":"CVE-2026-55559","score":0.00784,"percentile":0.5606,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-73mf-m39p-wpm9","url":"https://osv.dev/vulnerability/GHSA-73mf-m39p-wpm9","summary":"Yamcs vulnerable to Remote Code Execution via instance-template argument YAML injection (createInstance)","modified":"2026-08-28T17:40:35.569316Z","packages":[{"ecosystem":"Maven","name":"org.yamcs:yamcs-core","purl":"pkg:maven/org.yamcs/yamcs-core","ranges":[">=5.13.0 <5.13.2"],"fixed":["5.13.2"]},{"ecosystem":"Maven","name":"org.yamcs:yamcs-core","purl":"pkg:maven/org.yamcs/yamcs-core","ranges":["<5.12.8"],"fixed":["5.12.8"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}