CVE-2026-55559Critical· 9.8▾ MidnightYamcs 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…
▾ Midnight zone — Critical, or high with PoC / in-the-wild
impact 53.9 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Aug 29.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.6%
Last analysed / modified upstream
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.
Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Affected packages:
org.yamcs:yamcs-core >= 5.13.0, <= 5.13.1org.yamcs:yamcs-core <= 5.12.7Patched in:
org.yamcs:yamcs-core 5.13.2org.yamcs:yamcs-core 5.12.8Connected by shared product, vendor, weakness, or advisory.
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