CVE-2026-106121: RabbitMQ: JSONReader in the default JSON-RPC mapper never terminates on truncated input, causing DoS

com.rabbitmq.tools.json.JSONReader.read() never returns when its input ends inside a quoted string or a // line comment. Both scanners walk the input with StringCharacterIterator.next() but only compare against a delimiter, so once the iterator reaches CharacterIterator.DONE (￿) they loop forever. The string scanner (string(), line 210, while (c != sep)) also appends ￿ to a StringBuilder every iteration, so it fills the heap and throws OutOfMemoryError, taking down the JVM. The comment scanner (skipWhiteSpace(), lines 89-92, while (c != '\n')) pins a thread at 100% CPU with no allocation.

This is reachable with a single message. JsonRpcServer and JsonRpcClient fall back to DefaultJsonRpcMapper whenever no mapper is passed (JsonRpcServer.java:84 and :114, JsonRpcClient.java:186), and that mapper hands the raw message body straight to JSONReader.read() (DefaultJsonRpcMapper.java:42 for the server request, :52 for the client reply). A caller that can publish to the RPC request queue hangs the server; a malicious or MITM’d JSON-RPC service does the same to a client.