fix: escape server-rendered account data

internal/server/handlers_admin.go

@@ -5,6 +5,7 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
+	"html"
 	"net/http"
 	"strings"
 	"time"
@@ -113,8 +114,8 @@ td{padding:0.5rem;border-bottom:1px solid #0f3460}a{color:#4ecca3}</style></head
 		if u["blocked"].(int) != 0 {
 			blocked = "🚫"
 		}
-		w.Write([]byte(`<tr><td>` + u["username"].(string) + `</td><td>` + u["email"].(string) +
+		w.Write([]byte(`<tr><td>` + html.EscapeString(u["username"].(string)) + `</td><td>` + html.EscapeString(u["email"].(string)) +
-			`</td><td>` + confirmed + `</td><td>` + blocked + `</td><td>` + u["created_at"].(string) + `</td></tr>`))
+			`</td><td>` + confirmed + `</td><td>` + blocked + `</td><td>` + html.EscapeString(u["created_at"].(string)) + `</td></tr>`))
 	}
 	w.Write([]byte(`</table></body></html>`))
 }
@@ -148,8 +149,8 @@ td{padding:0.5rem;border-bottom:1px solid #0f3460}a{color:#4ecca3}</style></head
 		if revokedAt == "" {
 			revokedAt = "-"
 		}
-		w.Write([]byte(`<tr><td>` + name + `</td><td style="font-family:monospace;font-size:0.8em">` + id +
+		w.Write([]byte(`<tr><td>` + html.EscapeString(name) + `</td><td style="font-family:monospace;font-size:0.8em">` + html.EscapeString(id) +
-			`</td><td>` + clientVer + `</td><td>` + lastSeen + `</td><td>` + revokedAt + `</td><td>` + createdAt + `</td></tr>`))
+			`</td><td>` + html.EscapeString(clientVer) + `</td><td>` + html.EscapeString(lastSeen) + `</td><td>` + html.EscapeString(revokedAt) + `</td><td>` + html.EscapeString(createdAt) + `</td></tr>`))
 	}
 	w.Write([]byte(`</table></body></html>`))
 }

internal/server/handlers_web_user.go

@@ -4,8 +4,11 @@ import (
 	"crypto/rand"
 	"encoding/hex"
 	"fmt"
+	"html"
 	"log"
 	"net/http"
+	"net/url"
+	"strconv"
 	"strings"
 	"time"
 
@@ -187,8 +190,8 @@ func (s *Server) handleUserWebReset(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 		w.Header().Set("Content-Type", "text/html; charset=utf-8")
-		html := strings.ReplaceAll(resetPasswordHTML(locale), "{TOKEN}", token)
+		page := strings.ReplaceAll(resetPasswordHTML(locale), "{TOKEN}", html.EscapeString(token))
-		w.Write([]byte(html))
+		w.Write([]byte(page))
 	case "POST":
 		if err := r.ParseForm(); err != nil {
 			jsonErr(w, 400, "bad form")
@@ -204,12 +207,12 @@ func (s *Server) handleUserWebReset(w http.ResponseWriter, r *http.Request) {
 		}
 		if err := validatePassword(newPass); err != "" {
 			w.Header().Set("Content-Type", "text/html; charset=utf-8")
-			w.Write([]byte(errorPageHTML(locale, t(locale, "common.error"), string(err), "/reset?token="+token)))
+			w.Write([]byte(errorPageHTML(locale, t(locale, "common.error"), string(err), "/reset?token="+url.QueryEscape(token))))
 			return
 		}
 		if newPass != confirm {
 			w.Header().Set("Content-Type", "text/html; charset=utf-8")
-			w.Write([]byte(errorPageHTML(locale, t(locale, "common.error"), t(locale, "server.passwordsDoNotMatch"), "/reset?token="+token)))
+			w.Write([]byte(errorPageHTML(locale, t(locale, "common.error"), t(locale, "server.passwordsDoNotMatch"), "/reset?token="+url.QueryEscape(token))))
 			return
 		}
 		userID, err := s.resetPasswordWithToken(token, newPass)
@@ -310,7 +313,7 @@ func (s *Server) handleUserDashboard(w http.ResponseWriter, r *http.Request) {
 				created = created[:10]
 			}
 			status := "<span style='color:#34d399'>" + t(locale, "userDashboard.active") + "</span>"
-			revokeBtn := fmt.Sprintf(`<button class="btn btn-danger btn-sm" onclick="revokeDevice('%s')">%s</button>`, d.ID, t(locale, "userDashboard.revoke"))
+			revokeBtn := fmt.Sprintf(`<button class="btn btn-danger btn-sm" onclick="revokeDevice(%s)">%s</button>`, html.EscapeString(strconv.Quote(d.ID)), t(locale, "userDashboard.revoke"))
 			if d.RevokedAt != "" {
 				status = "<span style='color:#ff6b6b'>" + t(locale, "userDashboard.revoked") + "</span>"
 				revokeBtn = ""
@@ -321,11 +324,11 @@ func (s *Server) handleUserDashboard(w http.ResponseWriter, r *http.Request) {
 				<td>%s</td>
 				<td>%s</td>
 				<td>%s %s</td>
-			</tr>`, d.Name, status, created, ls, d.ClientVer, revokeBtn)
+			</tr>`, html.EscapeString(d.Name), status, html.EscapeString(created), html.EscapeString(ls), html.EscapeString(d.ClientVer), revokeBtn)
 		}
 	}
 
-	w.Write([]byte(userDashboardHTML(locale, username, deviceRows)))
+	w.Write([]byte(userDashboardHTML(locale, html.EscapeString(username), deviceRows)))
 }
 
 func (s *Server) handleUserWebLogout(w http.ResponseWriter, r *http.Request) {

internal/server/server_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"database/sql"
 	"encoding/json"
+	"html"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -372,6 +373,74 @@ func TestWebResetRejectsExpiredToken(t *testing.T) {
 	}
 }
 
+func TestServerRenderedPagesEscapeStoredValues(t *testing.T) {
+	s, _ := newSyncHTTPServer(t)
+	defer s.Close()
+
+	const maliciousText = `<img src=x onerror=alert(1)>`
+	const maliciousDeviceID = `device');alert(1);//`
+	now := time.Now().UTC().Format(time.RFC3339)
+	if _, err := s.db.Exec(`INSERT INTO server_users
+		(id, username, email, password_hash, confirmed, created_at)
+		VALUES (?, ?, ?, ?, 1, ?)`, "user-a", maliciousText, maliciousText+"@example.test", "unused", now); err != nil {
+		t.Fatalf("insert user: %v", err)
+	}
+	if _, err := s.db.Exec(`INSERT INTO server_devices
+		(id, name, api_key, user_id, vault_id, client_version, last_seen, created_at)
+		VALUES (?, ?, ?, ?, ?, ?, ?, ?)`, maliciousDeviceID, maliciousText, "device-key", "user-a", "vault-a", maliciousText, now, now); err != nil {
+		t.Fatalf("insert device: %v", err)
+	}
+	if _, err := s.db.Exec("INSERT INTO server_user_devices (user_id, device_id) VALUES (?, ?)", "user-a", maliciousDeviceID); err != nil {
+		t.Fatalf("link user device: %v", err)
+	}
+
+	tests := []struct {
+		name          string
+		path          string
+		cookie        *http.Cookie
+		containsDevID bool
+	}{
+		{
+			name:          "user dashboard",
+			path:          "/dashboard",
+			cookie:        &http.Cookie{Name: "user_session", Value: s.userTokens.Create("user-a")},
+			containsDevID: true,
+		},
+		{
+			name:   "admin users",
+			path:   "/admin/users",
+			cookie: &http.Cookie{Name: "admin_session", Value: s.tokens.Create()},
+		},
+		{
+			name:          "admin devices",
+			path:          "/admin/devices",
+			cookie:        &http.Cookie{Name: "admin_session", Value: s.tokens.Create()},
+			containsDevID: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodGet, tt.path, nil)
+			req.AddCookie(tt.cookie)
+			res := httptest.NewRecorder()
+			s.mux.ServeHTTP(res, req)
+			if res.Code != http.StatusOK {
+				t.Fatalf("status = %d, want 200", res.Code)
+			}
+			body := res.Body.String()
+			if strings.Contains(body, maliciousText) {
+				t.Fatalf("page contains unescaped stored text: %s", body)
+			}
+			if !strings.Contains(body, html.EscapeString(maliciousText)) {
+				t.Fatalf("page does not contain escaped stored text: %s", body)
+			}
+			if tt.containsDevID && strings.Contains(body, maliciousDeviceID) {
+				t.Fatalf("page contains unescaped device ID: %s", body)
+			}
+		})
+	}
+}
+
 func TestNewServerMigratesLegacyOperationScope(t *testing.T) {
 	dir := t.TempDir()
 	dbPath := filepath.Join(dir, "legacy.db")

internal/server/templates.go

@@ -2,6 +2,7 @@ package server
 
 import (
 	"fmt"
+	"html"
 	"strings"
 )
 
@@ -552,6 +553,9 @@ button:hover{background:#4f46e5}
 }
 
 func errorPageHTML(locale, title, msg, backURL string) string {
+	title = html.EscapeString(title)
+	msg = html.EscapeString(msg)
+	backURL = html.EscapeString(backURL)
 	return fmt.Sprintf(`<!DOCTYPE html>
 <html lang="ru">
 <head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">