diff --git a/CHANGELOG.md b/CHANGELOG.md
index 767cde7b1f..7bdb02ef93 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,7 +17,7 @@
 - DigitalOcean provider support added
 
 ## Important Notes
-N/A
+- (Security) Fix for open redirect vulnerability..  a bad actor using `/\` in redirect URIs can redirect a session to another domain
 
 ## Breaking Changes
 
diff --git a/oauthproxy.go b/oauthproxy.go
index a0195ea063..37019b48c3 100644
--- a/oauthproxy.go
+++ b/oauthproxy.go
@@ -558,7 +558,7 @@ func validOptionalPort(port string) bool {
 // IsValidRedirect checks whether the redirect URL is whitelisted
 func (p *OAuthProxy) IsValidRedirect(redirect string) bool {
 	switch {
-	case strings.HasPrefix(redirect, "/") && !strings.HasPrefix(redirect, "//"):
+	case strings.HasPrefix(redirect, "/") && !strings.HasPrefix(redirect, "//") && !strings.HasPrefix(redirect, "/\\"):
 		return true
 	case strings.HasPrefix(redirect, "http://") || strings.HasPrefix(redirect, "https://"):
 		redirectURL, err := url.Parse(redirect)