diff --git a/backend/internal/config/config.go b/backend/internal/config/config.go
index 147cc3e9..7d1b10e8 100644
--- a/backend/internal/config/config.go
+++ b/backend/internal/config/config.go
@@ -218,6 +218,8 @@ type SoraClientConfig struct {
 	MaxRetries            int               `mapstructure:"max_retries"`
 	PollIntervalSeconds   int               `mapstructure:"poll_interval_seconds"`
 	MaxPollAttempts       int               `mapstructure:"max_poll_attempts"`
+	RecentTaskLimit       int               `mapstructure:"recent_task_limit"`
+	RecentTaskLimitMax    int               `mapstructure:"recent_task_limit_max"`
 	Debug                 bool              `mapstructure:"debug"`
 	Headers               map[string]string `mapstructure:"headers"`
 	UserAgent             string            `mapstructure:"user_agent"`
@@ -230,6 +232,8 @@ type SoraStorageConfig struct {
 	LocalPath              string                   `mapstructure:"local_path"`
 	FallbackToUpstream     bool                     `mapstructure:"fallback_to_upstream"`
 	MaxConcurrentDownloads int                      `mapstructure:"max_concurrent_downloads"`
+	DownloadTimeoutSeconds int                      `mapstructure:"download_timeout_seconds"`
+	MaxDownloadBytes       int64                    `mapstructure:"max_download_bytes"`
 	Debug                  bool                     `mapstructure:"debug"`
 	Cleanup                SoraStorageCleanupConfig `mapstructure:"cleanup"`
 }
@@ -929,6 +933,8 @@ func setDefaults() {
 	viper.SetDefault("sora.client.max_retries", 3)
 	viper.SetDefault("sora.client.poll_interval_seconds", 2)
 	viper.SetDefault("sora.client.max_poll_attempts", 600)
+	viper.SetDefault("sora.client.recent_task_limit", 50)
+	viper.SetDefault("sora.client.recent_task_limit_max", 200)
 	viper.SetDefault("sora.client.debug", false)
 	viper.SetDefault("sora.client.headers", map[string]string{})
 	viper.SetDefault("sora.client.user_agent", "Sora/1.2026.007 (Android 15; 24122RKC7C; build 2600700)")
@@ -938,6 +944,8 @@ func setDefaults() {
 	viper.SetDefault("sora.storage.local_path", "")
 	viper.SetDefault("sora.storage.fallback_to_upstream", true)
 	viper.SetDefault("sora.storage.max_concurrent_downloads", 4)
+	viper.SetDefault("sora.storage.download_timeout_seconds", 120)
+	viper.SetDefault("sora.storage.max_download_bytes", int64(200<<20))
 	viper.SetDefault("sora.storage.debug", false)
 	viper.SetDefault("sora.storage.cleanup.enabled", true)
 	viper.SetDefault("sora.storage.cleanup.retention_days", 7)
@@ -1205,9 +1213,25 @@ func (c *Config) Validate() error {
 	if c.Sora.Client.MaxPollAttempts < 0 {
 		return fmt.Errorf("sora.client.max_poll_attempts must be non-negative")
 	}
+	if c.Sora.Client.RecentTaskLimit < 0 {
+		return fmt.Errorf("sora.client.recent_task_limit must be non-negative")
+	}
+	if c.Sora.Client.RecentTaskLimitMax < 0 {
+		return fmt.Errorf("sora.client.recent_task_limit_max must be non-negative")
+	}
+	if c.Sora.Client.RecentTaskLimitMax > 0 && c.Sora.Client.RecentTaskLimit > 0 &&
+		c.Sora.Client.RecentTaskLimitMax < c.Sora.Client.RecentTaskLimit {
+		c.Sora.Client.RecentTaskLimitMax = c.Sora.Client.RecentTaskLimit
+	}
 	if c.Sora.Storage.MaxConcurrentDownloads < 0 {
 		return fmt.Errorf("sora.storage.max_concurrent_downloads must be non-negative")
 	}
+	if c.Sora.Storage.DownloadTimeoutSeconds < 0 {
+		return fmt.Errorf("sora.storage.download_timeout_seconds must be non-negative")
+	}
+	if c.Sora.Storage.MaxDownloadBytes < 0 {
+		return fmt.Errorf("sora.storage.max_download_bytes must be non-negative")
+	}
 	if c.Sora.Storage.Cleanup.Enabled {
 		if c.Sora.Storage.Cleanup.RetentionDays <= 0 {
 			return fmt.Errorf("sora.storage.cleanup.retention_days must be positive")
diff --git a/backend/internal/service/sora_client.go b/backend/internal/service/sora_client.go
index 9ecb4688..f3a71a79 100644
--- a/backend/internal/service/sora_client.go
+++ b/backend/internal/service/sora_client.go
@@ -359,18 +359,43 @@ func (c *SoraDirectClient) CreateVideoTask(ctx context.Context, account *Account
 }
 
 func (c *SoraDirectClient) GetImageTask(ctx context.Context, account *Account, taskID string) (*SoraImageTaskStatus, error) {
-	token, err := c.getAccessToken(ctx, account)
+	status, found, err := c.fetchRecentImageTask(ctx, account, taskID, c.recentTaskLimit())
 	if err != nil {
 		return nil, err
 	}
-	headers := c.buildBaseHeaders(token, c.defaultUserAgent())
-	respBody, _, err := c.doRequest(ctx, account, http.MethodGet, c.buildURL("/v2/recent_tasks?limit=20"), headers, nil, false)
+	if found {
+		return status, nil
+	}
+	maxLimit := c.recentTaskLimitMax()
+	if maxLimit > 0 && maxLimit != c.recentTaskLimit() {
+		status, found, err = c.fetchRecentImageTask(ctx, account, taskID, maxLimit)
+		if err != nil {
+			return nil, err
+		}
+		if found {
+			return status, nil
+		}
+	}
+	return &SoraImageTaskStatus{ID: taskID, Status: "processing"}, nil
+}
+
+func (c *SoraDirectClient) fetchRecentImageTask(ctx context.Context, account *Account, taskID string, limit int) (*SoraImageTaskStatus, bool, error) {
+	token, err := c.getAccessToken(ctx, account)
 	if err != nil {
-		return nil, err
+		return nil, false, err
+	}
+	headers := c.buildBaseHeaders(token, c.defaultUserAgent())
+	if limit <= 0 {
+		limit = 20
+	}
+	endpoint := fmt.Sprintf("/v2/recent_tasks?limit=%d", limit)
+	respBody, _, err := c.doRequest(ctx, account, http.MethodGet, c.buildURL(endpoint), headers, nil, false)
+	if err != nil {
+		return nil, false, err
 	}
 	var resp map[string]any
 	if err := json.Unmarshal(respBody, &resp); err != nil {
-		return nil, err
+		return nil, false, err
 	}
 	taskResponses, _ := resp["task_responses"].([]any)
 	for _, item := range taskResponses {
@@ -401,10 +426,30 @@ func (c *SoraDirectClient) GetImageTask(ctx context.Context, account *Account, t
 				Status:      status,
 				ProgressPct: progress,
 				URLs:        urls,
-			}, nil
+			}, true, nil
 		}
 	}
-	return &SoraImageTaskStatus{ID: taskID, Status: "processing"}, nil
+	return &SoraImageTaskStatus{ID: taskID, Status: "processing"}, false, nil
+}
+
+func (c *SoraDirectClient) recentTaskLimit() int {
+	if c == nil || c.cfg == nil {
+		return 20
+	}
+	if c.cfg.Sora.Client.RecentTaskLimit > 0 {
+		return c.cfg.Sora.Client.RecentTaskLimit
+	}
+	return 20
+}
+
+func (c *SoraDirectClient) recentTaskLimitMax() int {
+	if c == nil || c.cfg == nil {
+		return 0
+	}
+	if c.cfg.Sora.Client.RecentTaskLimitMax > 0 {
+		return c.cfg.Sora.Client.RecentTaskLimitMax
+	}
+	return 0
 }
 
 func (c *SoraDirectClient) GetVideoTask(ctx context.Context, account *Account, taskID string) (*SoraVideoTaskStatus, error) {
diff --git a/backend/internal/service/sora_client_test.go b/backend/internal/service/sora_client_test.go
index abbe47a1..a6bf71cd 100644
--- a/backend/internal/service/sora_client_test.go
+++ b/backend/internal/service/sora_client_test.go
@@ -52,3 +52,36 @@ func TestSoraDirectClient_BuildBaseHeaders(t *testing.T) {
 	require.Equal(t, "yes", headers.Get("X-Test"))
 	require.Empty(t, headers.Get("openai-sentinel-token"))
 }
+
+func TestSoraDirectClient_GetImageTaskFallbackLimit(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		limit := r.URL.Query().Get("limit")
+		w.Header().Set("Content-Type", "application/json")
+		switch limit {
+		case "1":
+			_, _ = w.Write([]byte(`{"task_responses":[]}`))
+		case "2":
+			_, _ = w.Write([]byte(`{"task_responses":[{"id":"task-1","status":"completed","progress_pct":1,"generations":[{"url":"https://example.com/a.png"}]}]}`))
+		default:
+			_, _ = w.Write([]byte(`{"task_responses":[]}`))
+		}
+	}))
+	defer server.Close()
+
+	cfg := &config.Config{
+		Sora: config.SoraConfig{
+			Client: config.SoraClientConfig{
+				BaseURL:            server.URL,
+				RecentTaskLimit:    1,
+				RecentTaskLimitMax: 2,
+			},
+		},
+	}
+	client := NewSoraDirectClient(cfg, nil, nil)
+	account := &Account{Credentials: map[string]any{"access_token": "token"}}
+
+	status, err := client.GetImageTask(context.Background(), account, "task-1")
+	require.NoError(t, err)
+	require.Equal(t, "completed", status.Status)
+	require.Equal(t, []string{"https://example.com/a.png"}, status.URLs)
+}
diff --git a/backend/internal/service/sora_gateway_service.go b/backend/internal/service/sora_gateway_service.go
index 49cd7bba..ea696d63 100644
--- a/backend/internal/service/sora_gateway_service.go
+++ b/backend/internal/service/sora_gateway_service.go
@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"io"
 	"mime"
+	"net"
 	"net/http"
 	"net/url"
 	"regexp"
@@ -26,6 +27,9 @@ var soraImageMarkdownRe = regexp.MustCompile(`!\[[^\]]*\]\(([^)]+)\)`)
 var soraVideoHTMLRe = regexp.MustCompile(`(?i)<video[^>]+src=['"]([^'"]+)['"]`)
 
 const soraRewriteBufferLimit = 2048
+const soraImageInputMaxBytes = 20 << 20
+const soraImageInputMaxRedirects = 3
+const soraImageInputTimeout = 20 * time.Second
 
 var soraImageSizeMap = map[string]string{
 	"gpt-image":           "360",
@@ -33,6 +37,29 @@ var soraImageSizeMap = map[string]string{
 	"gpt-image-portrait":  "540",
 }
 
+var soraBlockedHostnames = map[string]struct{}{
+	"localhost":                 {},
+	"localhost.localdomain":     {},
+	"metadata.google.internal":  {},
+	"metadata.google.internal.": {},
+}
+
+var soraBlockedCIDRs = mustParseCIDRs([]string{
+	"0.0.0.0/8",
+	"10.0.0.0/8",
+	"100.64.0.0/10",
+	"127.0.0.0/8",
+	"169.254.0.0/16",
+	"172.16.0.0/12",
+	"192.168.0.0/16",
+	"224.0.0.0/4",
+	"240.0.0.0/4",
+	"::/128",
+	"::1/128",
+	"fc00::/7",
+	"fe80::/10",
+})
+
 type soraStreamingResult struct {
 	mediaType    string
 	mediaURLs    []string
@@ -1233,11 +1260,24 @@ func decodeSoraImageInput(ctx context.Context, input string) ([]byte, string, er
 }
 
 func downloadSoraImageInput(ctx context.Context, rawURL string) ([]byte, string, error) {
-	req, err := http.NewRequestWithContext(ctx, http.MethodGet, rawURL, nil)
+	parsed, err := validateSoraImageURL(rawURL)
 	if err != nil {
 		return nil, "", err
 	}
-	resp, err := http.DefaultClient.Do(req)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, parsed.String(), nil)
+	if err != nil {
+		return nil, "", err
+	}
+	client := &http.Client{
+		Timeout: soraImageInputTimeout,
+		CheckRedirect: func(req *http.Request, via []*http.Request) error {
+			if len(via) >= soraImageInputMaxRedirects {
+				return errors.New("too many redirects")
+			}
+			return validateSoraImageURLValue(req.URL)
+		},
+	}
+	resp, err := client.Do(req)
 	if err != nil {
 		return nil, "", err
 	}
@@ -1245,14 +1285,88 @@ func downloadSoraImageInput(ctx context.Context, rawURL string) ([]byte, string,
 	if resp.StatusCode != http.StatusOK {
 		return nil, "", fmt.Errorf("download image failed: %d", resp.StatusCode)
 	}
-	data, err := io.ReadAll(io.LimitReader(resp.Body, 20<<20))
+	data, err := io.ReadAll(io.LimitReader(resp.Body, soraImageInputMaxBytes))
 	if err != nil {
 		return nil, "", err
 	}
-	ext := fileExtFromURL(rawURL)
+	ext := fileExtFromURL(parsed.String())
 	if ext == "" {
 		ext = fileExtFromContentType(resp.Header.Get("Content-Type"))
 	}
 	filename := "image" + ext
 	return data, filename, nil
 }
+
+func validateSoraImageURL(raw string) (*url.URL, error) {
+	if strings.TrimSpace(raw) == "" {
+		return nil, errors.New("empty image url")
+	}
+	parsed, err := url.Parse(raw)
+	if err != nil {
+		return nil, fmt.Errorf("invalid image url: %w", err)
+	}
+	if err := validateSoraImageURLValue(parsed); err != nil {
+		return nil, err
+	}
+	return parsed, nil
+}
+
+func validateSoraImageURLValue(parsed *url.URL) error {
+	if parsed == nil {
+		return errors.New("invalid image url")
+	}
+	scheme := strings.ToLower(strings.TrimSpace(parsed.Scheme))
+	if scheme != "http" && scheme != "https" {
+		return errors.New("only http/https image url is allowed")
+	}
+	if parsed.User != nil {
+		return errors.New("image url cannot contain userinfo")
+	}
+	host := strings.ToLower(strings.TrimSpace(parsed.Hostname()))
+	if host == "" {
+		return errors.New("image url missing host")
+	}
+	if _, blocked := soraBlockedHostnames[host]; blocked {
+		return errors.New("image url is not allowed")
+	}
+	if ip := net.ParseIP(host); ip != nil {
+		if isSoraBlockedIP(ip) {
+			return errors.New("image url is not allowed")
+		}
+		return nil
+	}
+	ips, err := net.LookupIP(host)
+	if err != nil {
+		return fmt.Errorf("resolve image url failed: %w", err)
+	}
+	for _, ip := range ips {
+		if isSoraBlockedIP(ip) {
+			return errors.New("image url is not allowed")
+		}
+	}
+	return nil
+}
+
+func isSoraBlockedIP(ip net.IP) bool {
+	if ip == nil {
+		return true
+	}
+	for _, cidr := range soraBlockedCIDRs {
+		if cidr.Contains(ip) {
+			return true
+		}
+	}
+	return false
+}
+
+func mustParseCIDRs(values []string) []*net.IPNet {
+	out := make([]*net.IPNet, 0, len(values))
+	for _, val := range values {
+		_, cidr, err := net.ParseCIDR(val)
+		if err != nil {
+			continue
+		}
+		out = append(out, cidr)
+	}
+	return out
+}
diff --git a/backend/internal/service/sora_gateway_service_test.go b/backend/internal/service/sora_gateway_service_test.go
index e4de8256..caa10427 100644
--- a/backend/internal/service/sora_gateway_service_test.go
+++ b/backend/internal/service/sora_gateway_service_test.go
@@ -97,3 +97,16 @@ func TestSoraGatewayService_BuildSoraMediaURLSigned(t *testing.T) {
 	require.Contains(t, url, "expires=")
 	require.Contains(t, url, "sig=")
 }
+
+func TestDecodeSoraImageInput_BlockPrivateURL(t *testing.T) {
+	_, _, err := decodeSoraImageInput(context.Background(), "http://127.0.0.1/internal.png")
+	require.Error(t, err)
+}
+
+func TestDecodeSoraImageInput_DataURL(t *testing.T) {
+	encoded := "data:image/png;base64,aGVsbG8="
+	data, filename, err := decodeSoraImageInput(context.Background(), encoded)
+	require.NoError(t, err)
+	require.NotEmpty(t, data)
+	require.Contains(t, filename, ".png")
+}
diff --git a/backend/internal/service/sora_media_storage.go b/backend/internal/service/sora_media_storage.go
index 53214bb7..4359f78d 100644
--- a/backend/internal/service/sora_media_storage.go
+++ b/backend/internal/service/sora_media_storage.go
@@ -30,6 +30,8 @@ type SoraMediaStorage struct {
 	imageRoot          string
 	videoRoot          string
 	maxConcurrent      int
+	downloadTimeout    time.Duration
+	maxDownloadBytes   int64
 	fallbackToUpstream bool
 	debug              bool
 	sem                chan struct{}
@@ -92,6 +94,17 @@ func (s *SoraMediaStorage) refreshConfig() {
 		maxConcurrent = 4
 	}
 	s.maxConcurrent = maxConcurrent
+	timeoutSeconds := s.cfg.Sora.Storage.DownloadTimeoutSeconds
+	if timeoutSeconds <= 0 {
+		timeoutSeconds = 120
+	}
+	s.downloadTimeout = time.Duration(timeoutSeconds) * time.Second
+
+	maxBytes := s.cfg.Sora.Storage.MaxDownloadBytes
+	if maxBytes <= 0 {
+		maxBytes = 200 << 20
+	}
+	s.maxDownloadBytes = maxBytes
 	s.fallbackToUpstream = s.cfg.Sora.Storage.FallbackToUpstream
 	s.debug = s.cfg.Sora.Storage.Debug
 	s.sem = make(chan struct{}, maxConcurrent)
@@ -180,7 +193,8 @@ func (s *SoraMediaStorage) downloadOnce(ctx context.Context, root, mediaType, ra
 	if err != nil {
 		return "", err
 	}
-	resp, err := http.DefaultClient.Do(req)
+	client := &http.Client{Timeout: s.downloadTimeout}
+	resp, err := client.Do(req)
 	if err != nil {
 		return "", err
 	}
@@ -198,6 +212,9 @@ func (s *SoraMediaStorage) downloadOnce(ctx context.Context, root, mediaType, ra
 	if ext == "" {
 		ext = ".bin"
 	}
+	if s.maxDownloadBytes > 0 && resp.ContentLength > s.maxDownloadBytes {
+		return "", fmt.Errorf("download size exceeds limit: %d", resp.ContentLength)
+	}
 
 	datePath := time.Now().Format("2006/01/02")
 	destDir := filepath.Join(root, filepath.FromSlash(datePath))
@@ -212,10 +229,16 @@ func (s *SoraMediaStorage) downloadOnce(ctx context.Context, root, mediaType, ra
 	}
 	defer func() { _ = out.Close() }()
 
-	if _, err := io.Copy(out, resp.Body); err != nil {
+	limited := io.LimitReader(resp.Body, s.maxDownloadBytes+1)
+	written, err := io.Copy(out, limited)
+	if err != nil {
 		_ = os.Remove(destPath)
 		return "", err
 	}
+	if s.maxDownloadBytes > 0 && written > s.maxDownloadBytes {
+		_ = os.Remove(destPath)
+		return "", fmt.Errorf("download size exceeds limit: %d", written)
+	}
 
 	relative := path.Join("/", mediaType, datePath, filename)
 	if s.debug {
diff --git a/backend/internal/service/sora_media_storage_test.go b/backend/internal/service/sora_media_storage_test.go
index f86234d2..0050afed 100644
--- a/backend/internal/service/sora_media_storage_test.go
+++ b/backend/internal/service/sora_media_storage_test.go
@@ -67,3 +67,27 @@ func TestSoraMediaStorage_FallbackToUpstream(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, []string{url}, urls)
 }
+
+func TestSoraMediaStorage_MaxDownloadBytes(t *testing.T) {
+	tmpDir := t.TempDir()
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "image/png")
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("too-large"))
+	}))
+	defer server.Close()
+
+	cfg := &config.Config{
+		Sora: config.SoraConfig{
+			Storage: config.SoraStorageConfig{
+				Type:             "local",
+				LocalPath:        tmpDir,
+				MaxDownloadBytes: 1,
+			},
+		},
+	}
+
+	storage := NewSoraMediaStorage(cfg)
+	_, err := storage.StoreFromURLs(context.Background(), "image", []string{server.URL + "/img.png"})
+	require.Error(t, err)
+}
diff --git a/deploy/config.example.yaml b/deploy/config.example.yaml
index 2c7a1778..9ef3ee5c 100644
--- a/deploy/config.example.yaml
+++ b/deploy/config.example.yaml
@@ -269,6 +269,12 @@ sora:
     # Max poll attempts
     # 最大轮询次数
     max_poll_attempts: 600
+    # Recent task query limit (image)
+    # 最近任务查询数量（图片轮询）
+    recent_task_limit: 50
+    # Recent task query max limit (fallback)
+    # 最近任务查询最大数量（回退）
+    recent_task_limit_max: 200
     # Enable debug logs for Sora upstream requests
     # 启用 Sora 直连调试日志
     debug: false
@@ -294,6 +300,12 @@ sora:
     # Max concurrent downloads
     # 并发下载上限
     max_concurrent_downloads: 4
+    # Download timeout (seconds)
+    # 下载超时（秒）
+    download_timeout_seconds: 120
+    # Max download bytes
+    # 最大下载字节数
+    max_download_bytes: 209715200
     # Enable debug logs for media storage
     # 启用媒体存储调试日志
     debug: false