Summary
nosurf vulnerable to CSRF due to non-functional same-origin request checks
Details
Due to misuse of the Go net/http library, nosurf categorizes all incoming requests as plain-text HTTP requests, in which case the Referer header is not checked to have the same origin as the target webpage.
If the attacker has control over HTML contents on either the target website (e.g. example.com), or on a website hosted on a subdomain of the target (e.g. attacker.example.com), they will also be able to manipulate cookies set for the target website. By acquiring the secret CSRF token from the cookie, or overriding the cookie with a new token known to the attacker, attacker.example.com is able to craft cross-site requests to example.com.
Workarounds
In lieu of upgrading to a patched version of nosurf, users may additionally use another HTTP middleware to ensure that a non-safe HTTP request is coming from the same origin (e.g. by requiring a Sec-Fetch-Site: same-origin header in the request).
References
https://github.com/advisories/GHSA-rq77-p4h8-4crw
https://github.com/justinas/nosurf-cve-2025-46721
https://www.cve.org/CVERecord?id=CVE-2025-46721
https://github.com/justinas/nosurf/releases/tag/v1.2.0
Impact
This vulnerability allows an attacker who controls content on the target site, or on a subdomain of the target site (either via XSS, or otherwise) to bypass Cross-Site Request Forgery checks and issue requests on user's behalf.
A victim's authenticated browser session is used to submit forged requests to an application that cannot distinguish them from legitimate ones. Typical impact: state-changing actions performed as the victim without their consent.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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A patch for the issue was released in nosurf 1.2.0.
Frequently Asked Questions
- What is CVE-2025-46721? CVE-2025-46721 is a medium-severity cross-site request forgery (CSRF) vulnerability in github.com/justinas/nosurf (go), affecting versions < 1.2.0. It is fixed in 1.2.0. A victim's authenticated browser session is used to submit forged requests to an application that cannot distinguish them from legitimate ones.
- Which versions of github.com/justinas/nosurf are affected by CVE-2025-46721? github.com/justinas/nosurf (go) versions < 1.2.0 is affected.
- Is there a fix for CVE-2025-46721? Yes. CVE-2025-46721 is fixed in 1.2.0. Upgrade to this version or later.
- Is CVE-2025-46721 exploitable, and should I be worried? Whether CVE-2025-46721 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-46721 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2025-46721? Upgrade
github.com/justinas/nosurfto 1.2.0 or later.