diff --git a/lib/http.go b/lib/http.go
index 65f96400..60e51d4f 100644
--- a/lib/http.go
+++ b/lib/http.go
@@ -296,6 +296,16 @@ func (s *Server) constructRedirectURL(r *http.Request) (string, error) {
 	if proto == "" || host == "" || uri == "" {
 		return "", errors.New(localizer.T("missing_required_forwarded_headers"))
 	}
+
+	switch proto {
+	case "http", "https":
+		// allowed
+	default:
+		lg := internal.GetRequestLogger(s.logger, r)
+		lg.Warn("invalid protocol in X-Forwarded-Proto", "proto", proto)
+		return "", errors.New(localizer.T("invalid_redirect"))
+	}
+
 	// Check if host is allowed in RedirectDomains (supports '*' via glob)
 	if len(s.opts.RedirectDomains) > 0 && !matchRedirectDomain(s.opts.RedirectDomains, host) {
 		lg := internal.GetRequestLogger(s.logger, r)
@@ -369,16 +379,31 @@ func (s *Server) ServeHTTPNext(w http.ResponseWriter, r *http.Request) {
 		localizer := localization.GetLocalizer(r)
 
 		redir := r.FormValue("redir")
-		urlParsed, err := r.URL.Parse(redir)
+		urlParsed, err := url.ParseRequestURI(redir)
 		if err != nil {
-			s.respondWithStatus(w, r, localizer.T("redirect_not_parseable"), makeCode(err), http.StatusBadRequest)
+			// if ParseRequestURI fails, try as relative URL
+			urlParsed, err = r.URL.Parse(redir)
+			if err != nil {
+				s.respondWithStatus(w, r, localizer.T("redirect_not_parseable"), makeCode(err), http.StatusBadRequest)
+				return
+			}
+		}
+
+		// validate URL scheme to prevent javascript:, data:, file:, tel:, etc.
+		switch urlParsed.Scheme {
+		case "", "http", "https":
+			// allowed: empty scheme means relative URL
+		default:
+			lg := internal.GetRequestLogger(s.logger, r)
+			lg.Warn("XSS attempt blocked, invalid redirect scheme", "scheme", urlParsed.Scheme, "redir", redir)
+			s.respondWithStatus(w, r, localizer.T("invalid_redirect"), "", http.StatusBadRequest)
 			return
 		}
 
 		hostNotAllowed := len(urlParsed.Host) > 0 &&
 			len(s.opts.RedirectDomains) != 0 &&
 			!matchRedirectDomain(s.opts.RedirectDomains, urlParsed.Host)
-		hostMismatch := r.URL.Host != "" && urlParsed.Host != r.URL.Host
+		hostMismatch := r.URL.Host != "" && urlParsed.Host != "" && urlParsed.Host != r.URL.Host
 
 		if hostNotAllowed || hostMismatch {
 			lg := internal.GetRequestLogger(s.logger, r)
diff --git a/lib/redirect_security_test.go b/lib/redirect_security_test.go
new file mode 100644
index 00000000..e16206a3
--- /dev/null
+++ b/lib/redirect_security_test.go
@@ -0,0 +1,296 @@
+package lib
+
+import (
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"testing"
+
+	"github.com/TecharoHQ/anubis/lib/policy"
+)
+
+func TestRedirectSecurity(t *testing.T) {
+	tests := []struct {
+		name     string
+		testType string // "constructRedirectURL", "serveHTTPNext", "renderIndex"
+
+		// For constructRedirectURL tests
+		xForwardedProto string
+		xForwardedHost  string
+		xForwardedUri   string
+
+		// For serveHTTPNext tests
+		redirParam string
+		reqHost    string
+
+		// For renderIndex tests
+		returnHTTPStatusOnly bool
+
+		// Expected results
+		expectedStatus    int
+		shouldError       bool
+		shouldNotRedirect bool
+		shouldBlock       bool
+		errorContains     string
+	}{
+		// constructRedirectURL tests - X-Forwarded-Proto validation
+		{
+			name:            "constructRedirectURL: javascript protocol should be rejected",
+			testType:        "constructRedirectURL",
+			xForwardedProto: "javascript",
+			xForwardedHost:  "example.com",
+			xForwardedUri:   "alert(1)",
+			shouldError:     true,
+			errorContains:   "invalid",
+		},
+		{
+			name:            "constructRedirectURL: data protocol should be rejected",
+			testType:        "constructRedirectURL",
+			xForwardedProto: "data",
+			xForwardedHost:  "text/html",
+			xForwardedUri:   ",<script>alert(1)</script>",
+			shouldError:     true,
+			errorContains:   "invalid",
+		},
+		{
+			name:            "constructRedirectURL: file protocol should be rejected",
+			testType:        "constructRedirectURL",
+			xForwardedProto: "file",
+			xForwardedHost:  "",
+			xForwardedUri:   "/etc/passwd",
+			shouldError:     true,
+			errorContains:   "invalid",
+		},
+		{
+			name:            "constructRedirectURL: ftp protocol should be rejected",
+			testType:        "constructRedirectURL",
+			xForwardedProto: "ftp",
+			xForwardedHost:  "example.com",
+			xForwardedUri:   "/file.txt",
+			shouldError:     true,
+			errorContains:   "invalid",
+		},
+		{
+			name:            "constructRedirectURL: https protocol should be allowed",
+			testType:        "constructRedirectURL",
+			xForwardedProto: "https",
+			xForwardedHost:  "example.com",
+			xForwardedUri:   "/foo",
+			shouldError:     false,
+		},
+		{
+			name:            "constructRedirectURL: http protocol should be allowed",
+			testType:        "constructRedirectURL",
+			xForwardedProto: "http",
+			xForwardedHost:  "example.com",
+			xForwardedUri:   "/bar",
+			shouldError:     false,
+		},
+
+		// serveHTTPNext tests - redir parameter validation
+		{
+			name:              "serveHTTPNext: javascript: URL should be rejected",
+			testType:          "serveHTTPNext",
+			redirParam:        "javascript:alert(1)",
+			reqHost:           "example.com",
+			expectedStatus:    http.StatusBadRequest,
+			shouldNotRedirect: true,
+		},
+		{
+			name:              "serveHTTPNext: data: URL should be rejected",
+			testType:          "serveHTTPNext",
+			redirParam:        "data:text/html,<script>alert(1)</script>",
+			reqHost:           "example.com",
+			expectedStatus:    http.StatusBadRequest,
+			shouldNotRedirect: true,
+		},
+		{
+			name:              "serveHTTPNext: file: URL should be rejected",
+			testType:          "serveHTTPNext",
+			redirParam:        "file:///etc/passwd",
+			reqHost:           "example.com",
+			expectedStatus:    http.StatusBadRequest,
+			shouldNotRedirect: true,
+		},
+		{
+			name:              "serveHTTPNext: vbscript: URL should be rejected",
+			testType:          "serveHTTPNext",
+			redirParam:        "vbscript:msgbox(1)",
+			reqHost:           "example.com",
+			expectedStatus:    http.StatusBadRequest,
+			shouldNotRedirect: true,
+		},
+		{
+			name:           "serveHTTPNext: valid https URL should work",
+			testType:       "serveHTTPNext",
+			redirParam:     "https://example.com/foo",
+			reqHost:        "example.com",
+			expectedStatus: http.StatusFound,
+		},
+		{
+			name:           "serveHTTPNext: valid relative URL should work",
+			testType:       "serveHTTPNext",
+			redirParam:     "/foo/bar",
+			reqHost:        "example.com",
+			expectedStatus: http.StatusFound,
+		},
+		{
+			name:           "serveHTTPNext: external domain should be blocked",
+			testType:       "serveHTTPNext",
+			redirParam:     "https://evil.com/phishing",
+			reqHost:        "example.com",
+			expectedStatus: http.StatusBadRequest,
+			shouldBlock:    true,
+		},
+		{
+			name:           "serveHTTPNext: relative path should work",
+			testType:       "serveHTTPNext",
+			redirParam:     "/safe/path",
+			reqHost:        "example.com",
+			expectedStatus: http.StatusFound,
+		},
+		{
+			name:           "serveHTTPNext: empty redir should show success page",
+			testType:       "serveHTTPNext",
+			redirParam:     "",
+			reqHost:        "example.com",
+			expectedStatus: http.StatusOK,
+		},
+
+		// renderIndex tests - full subrequest auth flow
+		{
+			name:                 "renderIndex: javascript protocol in X-Forwarded-Proto",
+			testType:             "renderIndex",
+			xForwardedProto:      "javascript",
+			xForwardedHost:       "example.com",
+			xForwardedUri:        "alert(1)",
+			returnHTTPStatusOnly: true,
+			expectedStatus:       http.StatusBadRequest,
+		},
+		{
+			name:                 "renderIndex: data protocol in X-Forwarded-Proto",
+			testType:             "renderIndex",
+			xForwardedProto:      "data",
+			xForwardedHost:       "example.com",
+			xForwardedUri:        "text/html,<script>alert(1)</script>",
+			returnHTTPStatusOnly: true,
+			expectedStatus:       http.StatusBadRequest,
+		},
+		{
+			name:                 "renderIndex: valid https redirect",
+			testType:             "renderIndex",
+			xForwardedProto:      "https",
+			xForwardedHost:       "example.com",
+			xForwardedUri:        "/protected/page",
+			returnHTTPStatusOnly: true,
+			expectedStatus:       http.StatusTemporaryRedirect,
+		},
+	}
+
+	s := &Server{
+		opts: Options{
+			PublicUrl:       "https://anubis.example.com",
+			RedirectDomains: []string{},
+		},
+		logger: slog.Default(),
+		policy: &policy.ParsedConfig{},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			switch tt.testType {
+			case "constructRedirectURL":
+				req := httptest.NewRequest("GET", "/", nil)
+				req.Header.Set("X-Forwarded-Proto", tt.xForwardedProto)
+				req.Header.Set("X-Forwarded-Host", tt.xForwardedHost)
+				req.Header.Set("X-Forwarded-Uri", tt.xForwardedUri)
+
+				redirectURL, err := s.constructRedirectURL(req)
+
+				if tt.shouldError {
+					if err == nil {
+						t.Errorf("expected error containing %q, got nil", tt.errorContains)
+						t.Logf("got redirect URL: %s", redirectURL)
+					} else if tt.errorContains != "" && !strings.Contains(err.Error(), tt.errorContains) {
+						t.Logf("expected error containing %q, got: %v", tt.errorContains, err)
+					}
+				} else {
+					if err != nil {
+						t.Errorf("expected no error, got: %v", err)
+					}
+					// Verify the redirect URL is safe
+					if redirectURL != "" {
+						parsed, err := url.Parse(redirectURL)
+						if err != nil {
+							t.Errorf("failed to parse redirect URL: %v", err)
+						}
+						redirParam := parsed.Query().Get("redir")
+						if redirParam != "" {
+							redirParsed, err := url.Parse(redirParam)
+							if err != nil {
+								t.Errorf("failed to parse redir parameter: %v", err)
+							}
+							if redirParsed.Scheme != "http" && redirParsed.Scheme != "https" {
+								t.Errorf("redir parameter has unsafe scheme: %s", redirParsed.Scheme)
+							}
+						}
+					}
+				}
+
+			case "serveHTTPNext":
+				req := httptest.NewRequest("GET", "/.within.website/?redir="+url.QueryEscape(tt.redirParam), nil)
+				req.Host = tt.reqHost
+				req.URL.Host = tt.reqHost
+				rr := httptest.NewRecorder()
+
+				s.ServeHTTPNext(rr, req)
+
+				if rr.Code != tt.expectedStatus {
+					t.Errorf("expected status %d, got %d", tt.expectedStatus, rr.Code)
+					t.Logf("body: %s", rr.Body.String())
+				}
+
+				if tt.shouldNotRedirect {
+					location := rr.Header().Get("Location")
+					if location != "" {
+						t.Errorf("expected no redirect, but got Location header: %s", location)
+					}
+				}
+
+				if tt.shouldBlock {
+					location := rr.Header().Get("Location")
+					if location != "" && strings.Contains(location, "evil.com") {
+						t.Errorf("redirect to evil.com was not blocked: %s", location)
+					}
+				}
+
+			case "renderIndex":
+				req := httptest.NewRequest("GET", "/", nil)
+				req.Header.Set("X-Forwarded-Proto", tt.xForwardedProto)
+				req.Header.Set("X-Forwarded-Host", tt.xForwardedHost)
+				req.Header.Set("X-Forwarded-Uri", tt.xForwardedUri)
+
+				rr := httptest.NewRecorder()
+				s.RenderIndex(rr, req, policy.CheckResult{}, nil, tt.returnHTTPStatusOnly)
+
+				if rr.Code != tt.expectedStatus {
+					t.Errorf("expected status %d, got %d", tt.expectedStatus, rr.Code)
+				}
+
+				if tt.expectedStatus == http.StatusTemporaryRedirect {
+					location := rr.Header().Get("Location")
+					if location == "" {
+						t.Error("expected Location header, got none")
+					} else {
+						// Verify the location doesn't contain javascript:
+						if strings.Contains(location, "javascript") {
+							t.Errorf("Location header contains 'javascript': %s", location)
+						}
+					}
+				}
+			}
+		})
+	}
+}