#VU56234 Cross-site scripting in Next.js - CVE-2021-39178

Vulnerability identifier: #VU56234

Vulnerability risk: Low

CVSSv4.0: 1.2 [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/E:U/U:Clear]

CVE-ID: CVE-2021-39178

CWE-ID: CWE-79

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Next.js
Server applications / Frameworks for developing and running applications

Vendor: Zeit

Description

The disclosed vulnerability allows a remote attacker to perform cross-site scripting (XSS) attacks.

The vulnerability exists due to insufficient sanitization of user-supplied data in Image Optimization API. A remote attacker can trick the victim to follow a specially crafted link and execute arbitrary HTML and script code in user's browser in context of vulnerable website.

Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform phishing and drive-by-download attacks.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Next.js: 10.0.0 - 10.0.9, 10.1.0 - 10.1.3, 10.2.1 - 10.2.3, 11.0.0 - 11.0.1, 11.1.0

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External links
https://github.com/vercel/next.js/security/advisories/GHSA-9gr3-7897-pp7m
https://github.com/vercel/next.js/releases/tag/v11.1.1

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.