diff --git a/server-rs/crates/platform-matting/src/lib.rs b/server-rs/crates/platform-matting/src/lib.rs
index 82f5b0535..80bdaf407 100644
--- a/server-rs/crates/platform-matting/src/lib.rs
+++ b/server-rs/crates/platform-matting/src/lib.rs
@@ -38,6 +38,15 @@ const MAX_INPUT_BYTES: usize = 3 * 1024 * 1024;
 /// SegmentCommonImage 要求每条边大于 32 像素。
 const MIN_INPUT_EDGE: u32 = 32;
 
+/// 抠图结果下载的最大字节数。上游是阿里云返回的原尺寸 RGBA PNG，正常远小于此值；
+/// 设上限是为了防止异常 / 恶意上游用超大响应撑爆 API 进程内存（逐帧动画可并发多次调用）。
+/// 与 api-server BgFilter 降级路径的 `EDITOR_BACKGROUND_REMOVAL_MAX_RESPONSE_BYTES` 对齐。
+const MAX_RESULT_RESPONSE_BYTES: usize = 32 * 1024 * 1024;
+
+/// 抠图结果解码的最大边长像素。防止解码阶段按声明的巨幅尺寸分配像素缓冲。
+/// 与 api-server BgFilter 路径的 `EDITOR_BACKGROUND_REMOVAL_MAX_IMAGE_DIMENSION` 对齐。
+const MAX_RESULT_IMAGE_DIMENSION: u32 = 8192;
+
 #[derive(Clone, Debug)]
 pub struct MattingConfig {
     pub endpoint: String,
@@ -326,11 +335,7 @@ impl MattingClient {
             })
             .await?;
         let result_bytes = self.download_result_image(&result.image_url).await?;
-        let result_image = image::load_from_memory(&result_bytes)
-            .map_err(|error| {
-                MattingError::Upstream(format!("解析抠图结果图片失败：{error}"))
-            })?
-            .to_rgba8();
+        let result_image = decode_result_image(&result_bytes)?.to_rgba8();
 
         if !downscaled {
             if result_image.dimensions() != (source_width, source_height) {
@@ -360,7 +365,7 @@ impl MattingClient {
     }
 
     async fn download_result_image(&self, url: &str) -> Result<Vec<u8>, MattingError> {
-        let response = self
+        let mut response = self
             .client
             .get(url)
             .send()
@@ -375,13 +380,24 @@ impl MattingClient {
                 status.as_u16()
             )));
         }
-        response
-            .bytes()
-            .await
-            .map(|bytes| bytes.to_vec())
-            .map_err(|error| {
-                MattingError::Upstream(describe_result_download_body_error(&error))
-            })
+        // 先按 Content-Length 快速拒绝，再流式累加做兜底：不信任上游声明的长度，
+        // 逐块累计超阈值立即中断，避免 response.bytes() 一次性分配任意大小响应撑爆内存。
+        if response
+            .content_length()
+            .is_some_and(|length| length > MAX_RESULT_RESPONSE_BYTES as u64)
+        {
+            return Err(result_response_too_large_error());
+        }
+        let mut bytes = Vec::new();
+        while let Some(chunk) = response.chunk().await.map_err(|error| {
+            MattingError::Upstream(describe_result_download_body_error(&error))
+        })? {
+            if bytes.len().saturating_add(chunk.len()) > MAX_RESULT_RESPONSE_BYTES {
+                return Err(result_response_too_large_error());
+            }
+            bytes.extend_from_slice(chunk.as_ref());
+        }
+        Ok(bytes)
     }
 
     /// 把本地图片字节上传到 VIAPI 官方临时桶，返回可直接作为 ImageURL 的公网地址。
@@ -631,6 +647,31 @@ fn encode_rgba_png(image: &image::RgbaImage) -> Result<Vec<u8>, MattingError> {
     Ok(encoded)
 }
 
+fn result_response_too_large_error() -> MattingError {
+    MattingError::Upstream(format!(
+        "抠图结果响应过大，超过 {MAX_RESULT_RESPONSE_BYTES} 字节上限"
+    ))
+}
+
+/// 解码抠图结果时套上尺寸 / 分配上限，防止上游用巨幅尺寸声明在解码阶段撑爆内存。
+fn decode_result_image(bytes: &[u8]) -> Result<image::DynamicImage, MattingError> {
+    use std::io::Cursor;
+
+    let mut reader = image::ImageReader::new(Cursor::new(bytes))
+        .with_guessed_format()
+        .map_err(|error| {
+            MattingError::Upstream(format!("识别抠图结果格式失败：{error}"))
+        })?;
+    let mut limits = image::Limits::default();
+    limits.max_image_width = Some(MAX_RESULT_IMAGE_DIMENSION);
+    limits.max_image_height = Some(MAX_RESULT_IMAGE_DIMENSION);
+    limits.max_alloc = Some(MAX_RESULT_RESPONSE_BYTES as u64 * 4);
+    reader.limits(limits);
+    reader.decode().map_err(|error| {
+        MattingError::Upstream(format!("解析抠图结果图片失败：{error}"))
+    })
+}
+
 struct ViapiStsToken {
     access_key_id: String,
     access_key_secret: String,