GeoServer 2, in some configurations, allows remote attackers to execute arbitrary code via java.lang.Runtime.getRuntime().exec in wps:LiteralData within a wps:Execute request, as exploited in the wild in June 2023. NOTE: the vendor states that they are unable to reproduce this in any version.
https://isc.sans.edu/diary/29936
https://docs.geoserver.org/stable/en/user/services/wps/operations.html#execute