CVE-2024-34343: Cross-site Scripting (XSS) in navigateTo if used after SSR in nuxt
Summary The navigateTo function attempts to blockthe javascript: protocol, but does not correctly use API's provided by unjs/ufo. This library also contains parsing discrepancies.
Details The function first tests to see if the specified URL has a protocol. This uses the unjs/ufo package for URL parsing. This function works effectively, and returns true for a javascript: protocol.
After this, the URL is parsed using the parseURL function. This function will refuse to parse poorly formatted URLs. Parsing javascript:alert(1) returns null/"" for all values.
Next, the protocol of the URL is then checked using the isScriptProtocol function. This function simply checks the input against a list of protocols, and does not perform any parsing.
The combination of refusing to parse poorly formatted URLs, and not performing additional parsing means that script checks fail as no protocol can be found. Even if a protocol was identified, whitespace is not stripped in the parseURL implementation, bypassing the isScriptProtocol checks.
Certain special protocols are identified at the top of parseURL. Inserting a newline or tab into this sequence will block the special protocol check, and bypass the latter checks.
PoC POC - https://stackblitz.com/edit/nuxt-xss-navigateto?file=app.vue
Attempt payload X, then attempt payload Y.
Impact XSS, access to cookies, make requests on user's behalf.
Recommendations As always with these bugs, the URL constructor provided by the browser is always the safest method of parsing a URL.
Given the cross-platform requirements of nuxt/ufo a more appropriate solution is to make parsing consistent between functions, and to adapt parsing to be more consistent with the WHATWG URL specification.
Note I've reported this vulnerability here as it is unclear if this is a bug in ufo or a misuse of the ufo library.
This ONLY has impact after SSR has occurred, the javascript: protocol within a location header does not trigger XSS.
Other sources
Nuxt is a free and open-source framework to create full-stack web applications and websites with Vue.js. The navigateTo function attempts to blockthe javascript: protocol, but does not correctly use API's provided by unjs/ufo. This library also contains parsing discrepancies. The function first tests to see if the specified URL has a protocol. This uses the unjs/ufo package for URL parsing. This function works effectively, and returns true for a javascript: protocol. After this, the URL is parsed using the parseURL function. This function will refuse to parse poorly formatted URLs. Parsing javascript:alert(1) returns null/"" for all values. Next, the protocol of the URL is then checked using the isScriptProtocol function. This function simply checks the input against a list of protocols, and does not perform any parsing. The combination of refusing to parse poorly formatted URLs, and not performing additional parsing means that script checks fail as no protocol can be found. Even if a protocol was identified, whitespace is not stripped in the parseURL implementation, bypassing the isScriptProtocol checks. Certain special protocols are identified at the top of parseURL. Inserting a newline or tab into this sequence will block the special protocol check, and bypass the latter checks. This ONLY has impact after SSR has occured, the javascript: protocol within a location header does not trigger XSS. This issue has been addressed in release version 3.12.4 and all users are advised to upgrade. There are no known workarounds for this vulnerability.
— MITRE
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2024-34343?
CVE-2024-34343 has a high severity due to improper handling of the javascript: protocol in the navigateTo function.
How do I fix CVE-2024-34343?
To fix CVE-2024-34343, update the Nuxt package to version 3.12.4 or later.
What software is affected by CVE-2024-34343?
CVE-2024-34343 affects the Nuxt package version prior to 3.12.4.
What is the root cause of CVE-2024-34343?
The root cause of CVE-2024-34343 is a failure to correctly implement URL protocol blocking in the navigateTo function.
Can CVE-2024-34343 lead to security exploits?
Yes, CVE-2024-34343 could potentially lead to security exploits by allowing untrusted scripts to be executed via the javascript: protocol.