Find, fix and prevent vulnerabilities in your code.

Overview

@modelcontextprotocol/sdk is a Model Context Protocol implementation for TypeScript

Affected versions of this package are vulnerable to Missing Authorization via the InMemoryTaskStore implementation, where tasks created within one session are accessible to requests from other sessions. An attacker with access to a shared MCP server can read, modify, or retrieve results of tasks belonging to other users by supplying a known or guessed task ID, bypassing session-level isolation.

Note: This is only exploitable if the HTTP server passes taskStore to McpServer or Server.

Remediation

Upgrade @modelcontextprotocol/sdk to version 1.32.0 or higher.

References

• GitHub Advisory
• GitHub Commit
• GitHub PR

Overview

@modelcontextprotocol/sdk is a Model Context Protocol implementation for TypeScript

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the tools/call request handler in mcp.ts, where an attacker can send a tools/call request with a deeply nested or arbitrarily large arguments payload, causing unbounded recursive traversal of the input structure and exhausting server resources. The server performs no limit on the number of array elements or object members processed from tool-call arguments, allowing a remote attacker to crash the server process through resource exhaustion.

Remediation

Upgrade @modelcontextprotocol/sdk to version 1.32.0 or higher.

References

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

Overview

@modelcontextprotocol/sdk is a Model Context Protocol implementation for TypeScript

Affected versions of this package are vulnerable to Insufficiently Protected Credentials via the fetchToken and discardIfIssuerMismatch functions in the OAuth client authentication flow, where the SEP-2352 issuer check is not applied consistently. An attacker controlling a malicious authorization server can cause the client to send OAuth client credentials (client information) to an unintended server, because the issuer stamp on stored credentials is not validated before the token request is dispatched. This allows an attacker to harvest client credentials by redirecting token requests to a server whose issuer does not match the one the credentials were originally registered with.

Remediation

Upgrade @modelcontextprotocol/sdk to version 1.31.0 or higher.

References

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

Overview

fast-xml-parser is a Validate XML, Parse XML, Build XML without C/C++ based libraries

Affected versions of this package are vulnerable to XML Entity Expansion in the replaceEntitiesValue() function, which doesn't protect unlimited expansion of numeric entities the way it does DOCTYPE data (as described and fixed for CVE-2026-26278). An attacker can exhaust system memory and CPU resources by submitting XML input containing a large number of numeric character references - &#NNN; and &#xHH;.

Note: This is a bypass for the fix to the DOCTYPE expansion vulnerability in 5.3.6.

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 fast-xml-parser to version 5.5.6 or higher.

References

• GitHub Commit
• GitHub Release

Overview

music-metadata is a Music metadata parser for Node.js, supporting virtual any audio and tag format.

Affected versions of this package are vulnerable to Infinite loop through the parseExtensionObject process in the ASF parser when handling a sub-object with objectSize = 0. An attacker can cause the application to hang indefinitely by providing a specially crafted .asf file that triggers an infinite loop during parsing.

Remediation

Upgrade music-metadata to version 11.12.3 or higher.

References

• GitHub Commit
• GitHub PR
• GitHub Release

Overview

undici is an An HTTP/1.1 client, written from scratch for Node.js

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the handling of WebSocket message fragments. An attacker can cause unbounded memory growth and exhaust system resources by streaming a large number of small or empty continuation frames from a malicious WebSocket server.

Remediation

Upgrade undici to version 6.26.0, 7.28.0, 8.5.0 or higher.

References

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

Overview

undici is an An HTTP/1.1 client, written from scratch for Node.js

Affected versions of this package are vulnerable to Improper Handling of Highly Compressed Data (Data Amplification) in the PerMessageDeflate.decompress() method of the permessage-deflate extension. An attacker can cause excessive memory usage by sending specially crafted compressed WebSocket frames that decompress to a very large size, potentially leading to process crashes or unresponsiveness.

Remediation

Upgrade undici to version 6.24.0, 7.24.0 or higher.

References

• GitHub Commit
• HackerOne Report

Overview

undici is an An HTTP/1.1 client, written from scratch for Node.js

Affected versions of this package are vulnerable to Uncaught Exception through improper validation of the server_max_window_bits parameter in the permessage-deflate extension. An attacker can cause the process to terminate unexpectedly by sending a maliciously crafted value outside the valid range, which triggers an unhandled exception when the client attempts to create a zlib InflateRaw instance.

Remediation

Upgrade undici to version 6.24.0, 7.24.0 or higher.

References

• GitHub Commit
• HackerOne Report

Overview

undici is an An HTTP/1.1 client, written from scratch for Node.js

Affected versions of this package are vulnerable to Uncaught Exception via unhandled ERR_TLS_CERT_ALTNAME_INVALID errors in onHttpSocketError, onHttp2SessionError, and onHttp2SocketError. When a TLS connection is established and the server's certificate fails Subject Alternative Name validation post-connect, the error propagates and triggers a failed assert call, crashing the process. An attacker who can cause the client to connect to a server presenting an invalid TLS certificate can exploit this to crash the Node.js process.

Remediation

Upgrade undici to version 6.29.1, 7.30.1, 8.12.2 or higher.

References

• GitHub Advisory
• Vendor Advisory

Overview

zod is a TypeScript-first schema declaration and validation library with static type inference

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the handleArrayResult parse logic in $ZodArray, which accumulates every validation issue for each failing element in a large array with no cap or early termination. An attacker can submit a large array to an application using an array schema without a length constraint, causing the process to allocate excessive issue objects and crash due to out-of-memory conditions.

Remediation

Upgrade zod to version 4.6.6 or higher.

References

• GitHub Commit
• GitHub Issue
• GitHub Issue
• GitHub PR

Overview

pdfjs-dist is a Portable Document Format (PDF) library that is built with HTML5.

Affected versions of this package are vulnerable to Cross-site Scripting (XSS) via the enableScripting configuration when loading a crafted PDF file. An attacker can execute arbitrary JavaScript code in the context of the hosting domain by enticing a user to open a malicious PDF. This is only exploitable if enableScripting is set to true and no Content Security Policy is configured to disallow script-src.

Workaround

This vulnerability can be mitigated by setting enableScripting to false or by configuring a Content Security Policy to disallow script-src.

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 pdfjs-dist to version 6.2.108 or higher.

References

• GitHub Advisory
• Red Hat Bugzilla Bug

Overview

@modelcontextprotocol/sdk is a Model Context Protocol implementation for TypeScript

Affected versions of this package are vulnerable to Open Redirect via unconstrained redirect-following in the HTTP fetch layer used by auth.ts, sse.ts, and streamableHttp.ts. When the client performs OAuth metadata discovery, token requests, or client registration, it follows HTTP redirects without verifying that the redirect destination remains within the original request's origin. An attacker who can interpose a redirect response (for example, through a compromised or malicious server) can cause the client to send authentication credentials, OAuth tokens, or other sensitive headers to an attacker-controlled origin, resulting in credential exfiltration and limited request forgery.

Remediation

Upgrade @modelcontextprotocol/sdk to version 1.32.0 or higher.

References

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

Overview

undici is an An HTTP/1.1 client, written from scratch for Node.js

Affected versions of this package are vulnerable to Permissive List of Allowed Inputs via permissive substring matching in the Set-Cookie attribute parsing. An attacker can weaken cookie SameSite enforcement by crafting a response with a non-standard SameSite value that is interpreted as a more permissive setting, potentially allowing cookies to be sent in cross-site requests.

Note: This is only exploitable if the application consumes Set-Cookie headers from server responses (for example via undici's fetch or proxy code paths) and then forwards or relies on the parsed sameSite attribute.

Workaround

This vulnerability can be mitigated by validating that the parsed sameSite attribute is exactly 'Strict', 'Lax', or 'None' (case-insensitive) before relying on or forwarding it.

Remediation

Upgrade undici to version 6.27.0, 7.28.0, 8.5.0 or higher.

References

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

Overview

fast-xml-parser is a Validate XML, Parse XML, Build XML without C/C++ based libraries

Affected versions of this package are vulnerable to Improper Validation of Specified Quantity in Input in the DocTypeReader component when the maxEntityCount or maxEntitySize configuration options are explicitly set to 0. Due to JavaScript's falsy evaluation, the intended limits are bypassed. An attacker can cause unbounded entity expansion and exhaust server memory by supplying crafted XML input containing numerous large entities.

Note:

This is only exploitable if the application is configured with processEntities enabled and either maxEntityCount or maxEntitySize set to 0.

PoC

const { XMLParser } = require("fast-xml-parser");

// Developer intends: "no entities allowed at all"
const parser = new XMLParser({
  processEntities: {
    enabled: true,
    maxEntityCount: 0,    // should mean "zero entities allowed"
    maxEntitySize: 0       // should mean "zero-length entities only"
  }
});

// Generate XML with many large entities
let entities = "";
for (let i = 0; i < 1000; i++) {
  entities += `<!ENTITY e${i} "${"A".repeat(100000)}">`;
}

const xml = `<?xml version="1.0"?>
<!DOCTYPE foo [
  ${entities}
]>
<foo>&e0;</foo>`;

// This should throw "Entity count exceeds maximum" but does not
try {
  const result = parser.parse(xml);
  console.log("VULNERABLE: parsed without error, entities bypassed limits");
} catch (e) {
  console.log("SAFE:", e.message);
}

// Control test: setting maxEntityCount to 1 correctly blocks
const safeParser = new XMLParser({
  processEntities: {
    enabled: true,
    maxEntityCount: 1,
    maxEntitySize: 100
  }
});

try {
  safeParser.parse(xml);
  console.log("ERROR: should have thrown");
} catch (e) {
  console.log("CONTROL:", e.message);  // "Entity count (2) exceeds maximum allowed (1)"
}

Remediation

Upgrade fast-xml-parser to version 5.5.7 or higher.

References

• GitHub Advisory
• GitHub Commit

Overview

undici is an An HTTP/1.1 client, written from scratch for Node.js

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via unbounded automatic PONG write queuing in the WebSocket ByteParser receiver. A remote attacker can send a flood of PING control frames over a standard WebSocket connection, causing the outbound write queue to grow without bound because each inbound PING triggers an automatic PONG reply that is enqueued regardless of socket backpressure, exhausting memory and crashing the process.

Remediation

Upgrade undici to version 6.29.1, 7.30.1, 8.12.2 or higher.

References

• GitHub Advisory
• Vendor Advisory

Overview

@modelcontextprotocol/sdk is a Model Context Protocol implementation for TypeScript

Affected versions of this package are vulnerable to Incorrect Authorization via the verifyBearerToken function in bearer authentication middleware, which fails to validate the resource (audience) claim of incoming tokens against the expected resource identifier. An attacker in possession of a valid token issued for a different resource can present that token to gain unauthorized access, because the middleware accepts any token whose scopes match without confirming that the token's AuthInfo.resource corresponds to the intended server. This constitutes a token audience confusion attack, allowing cross-resource token reuse.

Remediation

Upgrade @modelcontextprotocol/sdk to version 1.32.0 or higher.

References

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

GPL-3.0 license