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nuxt vulnerable to Cross-site Scripting in navigateTo if used after SSR

Moderate severity GitHub Reviewed Published Aug 5, 2024 in nuxt/nuxt • Updated Aug 6, 2024

Package

npm nuxt (npm)

Affected versions

< 3.12.4

Patched versions

3.12.4

Description

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 occured, the javascript: protocol within a location header does not trigger XSS.

References

@danielroe danielroe published to nuxt/nuxt Aug 5, 2024
Published to the GitHub Advisory Database Aug 5, 2024
Reviewed Aug 5, 2024
Published by the National Vulnerability Database Aug 5, 2024
Last updated Aug 6, 2024

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required None
User interaction Active
Vulnerable System Impact Metrics
Confidentiality None
Integrity None
Availability None
Subsequent System Impact Metrics
Confidentiality Low
Integrity Low
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

EPSS score

0.043%
(10th percentile)

Weaknesses

CVE ID

CVE-2024-34343

GHSA ID

GHSA-vf6r-87q4-2vjf

Source code

Credits

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