REGEXVAULT
Dev & Systems/File Paths
ReDoS Checked

Windows UNC Path Regex for Go

/^\\{4}(?!\\)(?:[^\\/:*?"<>|\r\n]+(?:\\{1,2}|\/))+[^\\/:*?"<>|\r\n]+$/

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What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching windows unc path, ported and verified for Go. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. 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

Go
// Windows UNC Path
// ReDoS-checked | RegexVault — Dev & Systems > File Paths

package validation

import "regexp"

var windowsUncPathRe = regexp.MustCompile(`^\\{4}(?!\\)(?:[^\\/:*?"<>|\r\n]+(?:\\{1,2}|\/))+[^\\/:*?"<>|\r\n]+$`)

func ValidateWindowsUncPath(s string) bool {
    return windowsUncPathRe.MatchString(s)
}

// Example
// fmt.Println(ValidateWindowsUncPath("\\\\server\\share")) // true

Test Cases

Matches (Valid)
Rejects (Invalid)
\\\\server\\share\\\\server
\\\\fileserver\\shared-drive\\documents\\server\\share
\\\\10.0.0.1\\data\\reports//server/share
\\\\server.domain.com\\backup$\\2024\\\\server\\share<invalid>

When to use this pattern

This pattern is drawn from the Dev & Systems > File Paths category and has been checked for ReDoS risk. 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

UNC paths with attacker-controlled server names trigger NTLM authentication to the attacker, leaking password hashes. Never pass user-supplied UNC paths to Windows APIs without strict validation.

Technical Notes

Groups: 1=server name, 2=share name. Administrative shares end with $ (C$, ADMIN$). Avoid constructing UNC paths from user input — they can be used to capture NTLM hashes.

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