X-Frame-Options Header Regex for Go

What this pattern does

This page provides a well-structured, multi-part regular expression for matching x-frame-options header, ported and verified for Go. In security-sensitive code, using an unverified regex can open the door to both false positives and denial-of-service attacks. The snippet below is ready to drop into your Go project — whether you're validating in a Gin handler, a gRPC service, or a command-line tool.

Go Implementation

// X-Frame-Options Header
// ReDoS-safe | RegexVault — Security > Security Headers

package validation

import "regexp"

var xframeoptionsHeaderRe = regexp.MustCompile(`^(?:DENY|SAMEORIGIN|ALLOW-FROM\s+https?://[^\s]+)$`)

func ValidateXframeoptionsHeader(s string) bool {
    return xframeoptionsHeaderRe.MatchString(s)
}

// Example
// fmt.Println(ValidateXframeoptionsHeader("DENY")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Security > Security Headers category and carries a ReDoS-safe certification. That matters for Go developers because Go's RE2 engine is inherently safe from catastrophic backtracking, but this pattern has been additionally verified for correctness. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

X-Frame-Options prevents clickjacking by controlling iframe embedding. DENY: never in iframe. SAMEORIGIN: iframe on same origin only. ALLOW-FROM: deprecated (not supported by Chrome/Firefox). Modern alternative: CSP frame-ancestors directive, which is more flexible and widely supported.