Next.js version 6.0.0 introduces significant updates and improvements compared to the previous stable version 5.1.0, primarily focusing on leveraging the latest advancements in the Babel ecosystem. One of the most notable changes is the migration to Babel 7, evident in the updated @babel/* dependencies throughout the package. This transition brings performance enhancements, new language feature support, and improved standardization, empowering developers with cutting-edge JavaScript capabilities.
Several core dependencies like @babel/core, @babel/preset-env, @babel/preset-react, and various Babel plugins have been upgraded to beta versions aligning with Babel 7. This reflects a commitment to staying current with evolving JavaScript standards and offering developers access to the newest syntax and features. Besides the new Babel version, version 6.0.0 introduces the prop-types-exact package to ensure more strict PropTypes validation.
While the core functionality of Next.js remains the same, these dependency updates ensure better compatibility and performance. Developers upgrading from 5.1.0 should pay close attention to Babel configuration changes. Also, some packages present in the 5.1.0 like babel-preset-es2015 are removed. The update delivers enhancements underneath the hood and reflects Next.js's ongoing commitment to providing a modern and performant development experience for React applications.
All the vulnerabilities related to the version 6.0.0 of the package
Directory Traversal in Next.js
serverless targetnext exportWe recommend everyone to upgrade regardless of whether you can reproduce the issue or not.
https://github.com/zeit/next.js/releases/tag/v9.3.2
https://github.com/zeit/next.js/releases/tag/v9.3.2
Open Redirect in Next.js
Next.js is an open source website development framework to be used with the React library. In affected versions specially encoded paths could be used when pages/_error.js was statically generated, allowing an open redirect to occur to an external site. In general, this redirect does not directly harm users although it can allow for phishing attacks by redirecting to an attacker's domain from a trusted domain.
10.0.5 and 10.2.011.0.0 and 11.0.1 using pages/_error.js without getInitialProps11.0.0 and 11.0.1 using pages/_error.js and next exportpages/404.jsnext npm package hosted a different utility (0.4.1 being the latest version of that codebase), and this advisory does not apply to those versions.We recommend upgrading to the latest version of Next.js to improve the overall security of your application.
https://github.com/vercel/next.js/releases/tag/v11.1.0
Unexpected server crash in Next.js.
Next.js is a React framework. In versions of Next.js prior to 12.0.5 or 11.1.3, invalid or malformed URLs could lead to a server crash. In order to be affected by this issue, the deployment must use Next.js versions above 11.1.0 and below 12.0.5, Node.js above 15.0.0, and next start or a custom server. Deployments on Vercel are not affected, along with similar environments where invalid requests are filtered before reaching Next.js. Versions 12.0.5 and 11.1.3 contain patches for this issue. Note that prior version 0.9.9 package next hosted a different utility (0.4.1 being the latest version of that codebase), and this advisory does not apply to those versions.
Next.js missing cache-control header may lead to CDN caching empty reply
Next.js before 13.4.20-canary.13 lacks a cache-control header and thus empty prefetch responses may sometimes be cached by a CDN, causing a denial of service to all users requesting the same URL via that CDN. Cloudflare considers these requests cacheable assets.
Next.js Race Condition to Cache Poisoning
Summary
We received a responsible disclosure from Allam Rachid (zhero) for a low-severity race-condition vulnerability in Next.js. This issue only affects the Pages Router under certain misconfigurations, causing normal endpoints to serve pageProps data instead of standard HTML.
Credit
Thank you to Allam Rachid (zhero) for the responsible disclosure. This research was rewarded as part of our bug bounty program.
Next.js Affected by Cache Key Confusion for Image Optimization API Routes
A vulnerability in Next.js Image Optimization has been fixed in v15.4.5 and v14.2.31. When images returned from API routes vary based on request headers (such as Cookie or Authorization), these responses could be incorrectly cached and served to unauthorized users due to a cache key confusion bug.
All users are encouraged to upgrade if they use API routes to serve images that depend on request headers and have image optimization enabled.
More details at Vercel Changelog
Next.js Content Injection Vulnerability for Image Optimization
A vulnerability in Next.js Image Optimization has been fixed in v15.4.5 and v14.2.31. The issue allowed attacker-controlled external image sources to trigger file downloads with arbitrary content and filenames under specific configurations. This behavior could be abused for phishing or malicious file delivery.
All users relying on images.domains or images.remotePatterns are encouraged to upgrade and verify that external image sources are strictly validated.
More details at Vercel Changelog
Next.js Improper Middleware Redirect Handling Leads to SSRF
A vulnerability in Next.js Middleware has been fixed in v14.2.32 and v15.4.7. The issue occurred when request headers were directly passed into NextResponse.next(). In self-hosted applications, this could allow Server-Side Request Forgery (SSRF) if certain sensitive headers from the incoming request were reflected back into the response.
All users implementing custom middleware logic in self-hosted environments are strongly encouraged to upgrade and verify correct usage of the next() function.
More details at Vercel Changelog
send vulnerable to template injection that can lead to XSS
passing untrusted user input - even after sanitizing it - to SendStream.redirect() may execute untrusted code
this issue is patched in send 0.19.0
users are encouraged to upgrade to the patched version of express, but otherwise can workaround this issue by making sure any untrusted inputs are safe, ideally by validating them against an explicit allowlist
successful exploitation of this vector requires the following:
Prototype Pollution in Ajv
An issue was discovered in ajv.validate() in Ajv (aka Another JSON Schema Validator) 6.12.2. A carefully crafted JSON schema could be provided that allows execution of other code by prototype pollution. (While untrusted schemas are recommended against, the worst case of an untrusted schema should be a denial of service, not execution of code.)
Prototype Pollution in JSON5 via Parse Method
The parse method of the JSON5 library before and including version 2.2.1 does not restrict parsing of keys named __proto__, allowing specially crafted strings to pollute the prototype of the resulting object.
This vulnerability pollutes the prototype of the object returned by JSON5.parse and not the global Object prototype, which is the commonly understood definition of Prototype Pollution. However, polluting the prototype of a single object can have significant security impact for an application if the object is later used in trusted operations.
This vulnerability could allow an attacker to set arbitrary and unexpected keys on the object returned from JSON5.parse. The actual impact will depend on how applications utilize the returned object and how they filter unwanted keys, but could include denial of service, cross-site scripting, elevation of privilege, and in extreme cases, remote code execution.
This vulnerability is patched in json5 v2.2.2 and later. A patch has also been backported for json5 v1 in versions v1.0.2 and later.
Suppose a developer wants to allow users and admins to perform some risky operation, but they want to restrict what non-admins can do. To accomplish this, they accept a JSON blob from the user, parse it using JSON5.parse, confirm that the provided data does not set some sensitive keys, and then performs the risky operation using the validated data:
const JSON5 = require('json5');
const doSomethingDangerous = (props) => {
if (props.isAdmin) {
console.log('Doing dangerous thing as admin.');
} else {
console.log('Doing dangerous thing as user.');
}
};
const secCheckKeysSet = (obj, searchKeys) => {
let searchKeyFound = false;
Object.keys(obj).forEach((key) => {
if (searchKeys.indexOf(key) > -1) {
searchKeyFound = true;
}
});
return searchKeyFound;
};
const props = JSON5.parse('{"foo": "bar"}');
if (!secCheckKeysSet(props, ['isAdmin', 'isMod'])) {
doSomethingDangerous(props); // "Doing dangerous thing as user."
} else {
throw new Error('Forbidden...');
}
If the user attempts to set the isAdmin key, their request will be rejected:
const props = JSON5.parse('{"foo": "bar", "isAdmin": true}');
if (!secCheckKeysSet(props, ['isAdmin', 'isMod'])) {
doSomethingDangerous(props);
} else {
throw new Error('Forbidden...'); // Error: Forbidden...
}
However, users can instead set the __proto__ key to {"isAdmin": true}. JSON5 will parse this key and will set the isAdmin key on the prototype of the returned object, allowing the user to bypass the security check and run their request as an admin:
const props = JSON5.parse('{"foo": "bar", "__proto__": {"isAdmin": true}}');
if (!secCheckKeysSet(props, ['isAdmin', 'isMod'])) {
doSomethingDangerous(props); // "Doing dangerous thing as admin."
} else {
throw new Error('Forbidden...');
}
Denial of Service in mem
Versions of mem prior to 4.0.0 are vulnerable to Denial of Service (DoS). The package fails to remove old values from the cache even after a value passes its maxAge property. This may allow attackers to exhaust the system's memory if they are able to abuse the application logging.
Upgrade to version 4.0.0 or later.
yargs-parser Vulnerable to Prototype Pollution
Affected versions of yargs-parser are vulnerable to prototype pollution. Arguments are not properly sanitized, allowing an attacker to modify the prototype of Object, causing the addition or modification of an existing property that will exist on all objects.
Parsing the argument --foo.__proto__.bar baz' adds a bar property with value baz to all objects. This is only exploitable if attackers have control over the arguments being passed to yargs-parser.
Upgrade to versions 13.1.2, 15.0.1, 18.1.1 or later.
Prototype Pollution in minimist
Affected versions of minimist are vulnerable to prototype pollution. Arguments are not properly sanitized, allowing an attacker to modify the prototype of Object, causing the addition or modification of an existing property that will exist on all objects.
Parsing the argument --__proto__.y=Polluted adds a y property with value Polluted to all objects. The argument --__proto__=Polluted raises and uncaught error and crashes the application.
This is exploitable if attackers have control over the arguments being passed to minimist.
Upgrade to versions 0.2.1, 1.2.3 or later.
Prototype Pollution in minimist
Minimist prior to 1.2.6 and 0.2.4 is vulnerable to Prototype Pollution via file index.js, function setKey() (lines 69-95).
Uncontrolled Resource Consumption in ansi-html
This affects all versions of package ansi-html. If an attacker provides a malicious string, it will get stuck processing the input for an extremely long time.
node-fetch forwards secure headers to untrusted sites
node-fetch forwards secure headers such as authorization, www-authenticate, cookie, & cookie2 when redirecting to a untrusted site.
Regular Expression Denial of Service (ReDoS) in cross-spawn
Versions of the package cross-spawn before 7.0.5 are vulnerable to Regular Expression Denial of Service (ReDoS) due to improper input sanitization. An attacker can increase the CPU usage and crash the program by crafting a very large and well crafted string.
Prototype pollution in webpack loader-utils
Prototype pollution vulnerability in function parseQuery in parseQuery.js in webpack loader-utils prior to version 2.0.3 via the name variable in parseQuery.js.
loader-utils is vulnerable to Regular Expression Denial of Service (ReDoS) via url variable
A Regular expression denial of service (ReDoS) flaw was found in Function interpolateName in interpolateName.js in webpack loader-utils 2.0.0 via the url variable in interpolateName.js. A badly or maliciously formed string could be used to send crafted requests that cause a system to crash or take a disproportional amount of time to process. This issue has been patched in versions 1.4.2, 2.0.4 and 3.2.1.
loader-utils is vulnerable to Regular Expression Denial of Service (ReDoS)
A regular expression denial of service (ReDoS) flaw was found in Function interpolateName in interpolateName.js in webpack loader-utils via the resourcePath variable in interpolateName.js. A badly or maliciously formed string could be used to send crafted requests that cause a system to crash or take a disproportional amount of time to process. This issue has been patched in versions 1.4.2, 2.0.4 and 3.2.1.
path-to-regexp outputs backtracking regular expressions
A bad regular expression is generated any time you have two parameters within a single segment, separated by something that is not a period (.). For example, /:a-:b.
For users of 0.1, upgrade to 0.1.10. All other users should upgrade to 8.0.0.
These versions add backtrack protection when a custom regex pattern is not provided:
They do not protect against vulnerable user supplied capture groups. Protecting against explicit user patterns is out of scope for old versions and not considered a vulnerability.
Version 7.1.0 can enable strict: true and get an error when the regular expression might be bad.
Version 8.0.0 removes the features that can cause a ReDoS.
All versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom regular expression does not match the text before the parameter, you will be safe. For example, change /:a-:b to /:a-:b([^-/]+).
If paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length. For example, halving the attack string improves performance by 4x faster.
Using /:a-:b will produce the regular expression /^\/([^\/]+?)-([^\/]+?)\/?$/. This can be exploited by a path such as /a${'-a'.repeat(8_000)}/a. OWASP has a good example of why this occurs, but the TL;DR is the /a at the end ensures this route would never match but due to naive backtracking it will still attempt every combination of the :a-:b on the repeated 8,000 -a.
Because JavaScript is single threaded and regex matching runs on the main thread, poor performance will block the event loop and can lead to a DoS. In local benchmarks, exploiting the unsafe regex will result in performance that is over 1000x worse than the safe regex. In a more realistic environment using Express v4 and 10 concurrent connections, this translated to average latency of ~600ms vs 1ms.
Path traversal in webpack-dev-middleware
The webpack-dev-middleware middleware does not validate the supplied URL address sufficiently before returning the local file. It is possible to access any file on the developer's machine.
The middleware can either work with the physical filesystem when reading the files or it can use a virtualized in-memory memfs filesystem. If writeToDisk configuration option is set to true, the physical filesystem is used: https://github.com/webpack/webpack-dev-middleware/blob/7ed24e0b9f53ad1562343f9f517f0f0ad2a70377/src/utils/setupOutputFileSystem.js#L21
The getFilenameFromUrl method is used to parse URL and build the local file path. The public path prefix is stripped from the URL, and the unsecaped path suffix is appended to the outputPath: https://github.com/webpack/webpack-dev-middleware/blob/7ed24e0b9f53ad1562343f9f517f0f0ad2a70377/src/utils/getFilenameFromUrl.js#L82 As the URL is not unescaped and normalized automatically before calling the midlleware, it is possible to use %2e and %2f sequences to perform path traversal attack.
A blank project can be created containing the following configuration file webpack.config.js:
module.exports = { devServer: { devMiddleware: { writeToDisk: true } } };
When started, it is possible to access any local file, e.g. /etc/passwd:
$ curl localhost:8080/public/..%2f..%2f..%2f..%2f../etc/passwd
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
The developers using webpack-dev-server or webpack-dev-middleware are affected by the issue. When the project is started, an attacker might access any file on the developer's machine and exfiltrate the content (e.g. password, configuration files, private source code, ...).
If the development server is listening on a public IP address (or 0.0.0.0), an attacker on the local network can access the local files without any interaction from the victim (direct connection to the port).
If the server allows access from third-party domains (CORS, Allow-Access-Origin: * ), an attacker can send a malicious link to the victim. When visited, the client side script can connect to the local server and exfiltrate the local files.
The URL should be unescaped and normalized before any further processing.
Regular Expression Denial of Service (ReDoS)
npm ssri 5.2.2-6.0.1 and 7.0.0-8.0.0, processes SRIs using a regular expression which is vulnerable to a denial of service. Malicious SRIs could take an extremely long time to process, leading to denial of service. This issue only affects consumers using the strict option.
Cross-Site Scripting in serialize-javascript
Versions of serialize-javascript prior to 2.1.1 are vulnerable to Cross-Site Scripting (XSS). The package fails to sanitize serialized regular expressions. This vulnerability does not affect Node.js applications.
Upgrade to version 2.1.1 or later.
Insecure serialization leading to RCE in serialize-javascript
serialize-javascript prior to 3.1.0 allows remote attackers to inject arbitrary code via the function "deleteFunctions" within "index.js".
An object such as {"foo": /1"/, "bar": "a\"@__R-<UID>-0__@"} was serialized as {"foo": /1"/, "bar": "a\/1"/}, which allows an attacker to escape the bar key. This requires the attacker to control the values of both foo and bar and guess the value of <UID>. The UID has a keyspace of approximately 4 billion making it a realistic network attack.