UTF8DataInputJsonParser._reportInvalidToken() in FasterXML jackson-core builds the offending-token text for its error message by appending Java identifier characters to a StringBuilder in a loop that has no upper bound. Unlike the three sibling parser implementations, including UTF8StreamJsonParser, it never consults ErrorReportConfiguration.getMaxErrorTokenLength() (default 256). A malformed token supplied to a parser created through JsonFactory.createParser(DataInput) is therefore accumulated in full. No StreamReadConstraints setting mitigates this: maxDocumentLength cannot be applied to DataInput sources at all, and maxStringLength does not cover this path because the accumulation bypasses ReadConstrainedTextBuffer. The reporter measured a 20,000,109-character exception message from a 20-million-character malformed token on the DataInput path, against 367 characters for identical input on the InputStream path. Scaling the payload drives the StringBuilder, which also incurs byte-to-char expansion and internal array doubling, to many times the raw payload size and can trigger OutOfMemoryError for the whole JVM. UTF8DataInputJsonParser was introduced in 2.8.0 together with createParser(DataInput); releases before 2.8.0 do not contain the affected class.
No StreamReadConstraints or ErrorReportConfiguration setting mitigates this issue on the affected code path. Where possible, avoid JsonFactory.createParser(DataInput) for attacker-supplied content and use createParser(InputStream), createParser(Reader) or a byte-array overload instead; those parser implementations enforce maxErrorTokenLength correctly. Otherwise, bound input size ahead of the parser and cap JVM heap so that a single request cannot exhaust process memory.
Upgrade to com.fasterxml.jackson.core:jackson-core 2.18.11, 2.21.7 or 2.22.3, or to tools.jackson.core:jackson-core 3.1.7 or 3.2.3. The 2.8.x through 2.17.x, 2.19.x, 2.20.x and 3.0.x lines received no fix on their own branch and are no longer maintained upstream; consumers of those lines must move forward to a maintained release.