The stack below is based on an older version of snakeyaml but it objects to a valid json string notably coming from and org.json.JSONObject (some file contents redacted):
FATAL ERROR: while scanning a double-quoted scalar in 'string', line 1, column 3958: ... :"lalala","command":"foo ... ^ found unknown escape character /(47) in 'string', line 1, column 4037: ... ace.log 2\u003e/dev/null \u003c\/dev/null\u0026,","build_flags_b ... ^ at org.yaml.snakeyaml.scanner.ScannerImpl.scanFlowScalarNonSpaces(ScannerImpl.java:1911) at org.yaml.snakeyaml.scanner.ScannerImpl.scanFlowScalar(ScannerImpl.java:1848) at org.yaml.snakeyaml.scanner.ScannerImpl.fetchFlowScalar(ScannerImpl.java:1029) at org.yaml.snakeyaml.scanner.ScannerImpl.fetchDouble(ScannerImpl.java:1011)
From the source, it doesn't look like this is addressed at HEAD. AIUI forward slash is not called out in YAML 1.1 standard (which is oddly listed as current?), but is specifically added in 1.2 "for JSON compatibility"