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How the CVE Works
CVE-2025-46721 affects the Go library nosurf, a CSRF protection middleware. Versions before 1.2.0 incorrectly classify all incoming requests as plain-text HTTP, skipping the `Referer` header check. Attackers controlling content on the target site or its subdomain (e.g., via XSS) can manipulate cookies, extract CSRF tokens, or overwrite them. This allows crafting malicious requests from attacker-controlled subdomains (e.g., attacker.example.com) to the main domain (example.com). The flaw stems from improper use of Go’s `net/http` library, failing to enforce same-origin checks for unsafe requests.
DailyCVE Form
Platform: Go middleware
Version: <1.2.0
Vulnerability: CSRF bypass
Severity: Medium
Date: 06/23/2025
Prediction: Patch expected by 07/10/2025
What Undercode Say
// Vulnerable code snippet (nosurf <1.2.0)
func isSameOrigin(r http.Request) bool {
// Missing strict Referer check
return true // False assumption
}
// Mitigation (nosurf 1.2.0+)
func validateOrigin(r http.Request) bool {
referer := r.Header.Get("Referer")
return validateReferer(referer, r.Host)
}
How Exploit
1. Attacker injects malicious script on `attacker.example.com`.
2. Script steals/modifies CSRF token via cookie manipulation.
- Forges cross-site request to `example.com` with valid token.
Protection from this CVE
- Upgrade to nosurf 1.2.0+.
- Enforce
Sec-Fetch-Site: same-origin. - Implement additional origin-checking middleware.
Impact
- Unauthorized actions via CSRF.
- Session hijacking.
- Data integrity compromise.
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
