Find, fix and prevent vulnerabilities in your code.

Overview

parse-server is a version of the Parse backend that can be deployed to any infrastructure that can run Node.js.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) via the clientSDK parameter in the request-header parser. An attacker can exhaust CPU resources on a worker node by submitting an excessively long value for x-parse-client-version, causing eponential regex backtracking.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

• A The string must start with the letter 'A'
• (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
• D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

1. CCC
2. CC+C
3. C+CC
4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade parse-server to version 8.6.77, 9.9.1-alpha.1 or higher.

References

• GitHub Advisory
• GitHub PR
• GitHub PR

Overview

ws is a simple to use websocket client, server and console for node.js.

Affected versions of this package are vulnerable to Use of Uninitialized Resource in the websocket.close() implementation in the Sender class, which exposes uninitialized memory when a TypedArray is provided as the reason argument.

Note: The project maintainers note that this "flaw is only exploitable through misuse that is unlikely in practice".

PoC

import { deepStrictEqual } from 'node:assert';
import { WebSocket, WebSocketServer } from 'ws';

const wss = new WebSocketServer(
  { port: 0, skipUTF8Validation: true },
  function () {
    const { port } = wss.address();
    const ws = new WebSocket(`ws://localhost:${port}`, {
      skipUTF8Validation: true
    });

    ws.on('close', function (code, reason) {
      deepStrictEqual(reason, Buffer.alloc(80));
    });
  }
);

wss.on('connection', function (ws) {
  ws.close(1000, new Float32Array(20));
});

Remediation

Upgrade ws to version 8.20.1 or higher.

References

• GitHub Advisory
• GitHub Commit

Overview

parse-server is a version of the Parse backend that can be deployed to any infrastructure that can run Node.js.

Affected versions of this package are vulnerable to Information Exposure via the Did you mean ...? suggestions in GraphQL validation-error messages. An attacker can enumerate schema metadata, such as class names, field names, argument names, mutation names, and input-object fields, by sending malformed queries to the GraphQL endpoint.

Note:

1. This is only exploitable if the GraphQL API is enabled and the attacker is unauthenticated while graphQLPublicIntrospection is set to false.

2. This vulnerability bypasses the IntrospectionControlPlugin enforced when graphQLPublicIntrospection: false (the default) and defeats the schema-hiding goal of prior advisories CVE-2026-30854 and CVE-2025-53364.

Remediation

Upgrade parse-server to version 8.6.78, 9.9.1-alpha.2 or higher.

References

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

Overview

ip-address is an A library for parsing IPv4 and IPv6 IP addresses in node and the browser.

Affected versions of this package are vulnerable to Cross-site Scripting (XSS) via the group, link, and spanAll functions, as well as the parseMessage field of thrown errors. An attacker can execute arbitrary JavaScript in the context of the application by supplying crafted input that is rendered as HTML. This is only exploitable if untrusted input is passed to the relevant functions and their output is rendered as HTML (e.g., via innerHTML).

Workaround

This vulnerability can be mitigated by not passing untrusted input to the constructor, never rendering the output of the affected functions or error fields as HTML, treating these values as text only, sanitizing output with DOMPurify before inserting into the DOM, or validating input to reject zone identifiers or invalid characters.

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 ip-address to version 10.1.1 or higher.

References

• GitHub Advisory
• GitHub Commit

MPL-2.0 license