Affected: Maven: tools.jackson.core:jackson-core

## Summary

Jackson Core 3.x does not consistently enforce `StreamReadConstraints.maxDocumentLength`. Oversized JSON documents can be accepted without a `StreamConstraintsException` in multiple parser entry points, which allows configured size limits to be bypassed and weakens denial-of-service protections.

## Details

Three code paths where `maxDocumentLength` is not fully enforced:

### 1. Blocking parsers skip validation of the final in-memory buffer

Blocking parsers validate only previously processed buffers, not the final in-memory buffer:

- `ReaderBasedJsonParser.java:255` - `UTF8StreamJsonParser.java:208`

Relevant code:

```java _currInputProcessed += bufSize; _streamReadConstraints.validateDocumentLength(_currInputProcessed); ```

This means the check occurs only when a completed buffer is rolled over. If an oversized document is fully contained in the final buffer, parsing can complete without any document-length exception.

### 2. Async parsers skip validation of the final chunk on end-of-input

Async parsers validate previously processed chunks, but do not validate the final chunk on end-of-input:

- `NonBlockingByteArrayJsonParser.java:49` - `NonBlockingByteBufferJsonParser.java:57` - `NonBlockingUtf8JsonParserBase.java:75`

Relevant code:

```java _currInputProcessed += _origBufferLen; _streamReadConstraints.validateDocumentLength(_currInputProcessed);

public void endOfInput() { _endOfInput = true; } ```

`endOfInput()` marks EOF but does not perform a…