diff --git a/.changeset/spotty-cooks-trade.md b/.changeset/spotty-cooks-trade.md
new file mode 100644
index 000000000..c74c17533
--- /dev/null
+++ b/.changeset/spotty-cooks-trade.md
@@ -0,0 +1,5 @@
+---
+"@solidjs/start": patch
+---
+
+delete expired cookies in Single-Flight requests
diff --git a/packages/start/package.json b/packages/start/package.json
index 095ba2e68..2cef2dc18 100644
--- a/packages/start/package.json
+++ b/packages/start/package.json
@@ -69,6 +69,7 @@
     "@tanstack/server-functions-plugin": "1.121.21",
     "@vinxi/plugin-directives": "^0.5.0",
     "@vinxi/server-components": "^0.5.0",
+    "cookie-es": "^2.0.0",
     "defu": "^6.1.2",
     "error-stack-parser": "^2.1.4",
     "html-to-image": "^1.11.11",
diff --git a/packages/start/src/runtime/server-handler.ts b/packages/start/src/runtime/server-handler.ts
index 46e1603c5..74ded0de7 100644
--- a/packages/start/src/runtime/server-handler.ts
+++ b/packages/start/src/runtime/server-handler.ts
@@ -1,4 +1,5 @@
 /// <reference types="vinxi/types/server" />
+import { parseSetCookie } from "cookie-es";
 import { crossSerializeStream, fromJSON, getCrossReferenceHeader } from "seroval";
 // @ts-ignore
 import {
@@ -322,9 +323,16 @@ function createSingleFlightHeaders(sourceEvent: FetchEvent) {
   }
   SetCookies.forEach(cookie => {
     if (!cookie) return;
-    const keyValue = cookie.split(";")[0]!;
-    const [key, value] = keyValue.split("=");
-    key && value && (cookies[key] = value);
+    const { maxAge, expires, name, value } = parseSetCookie(cookie);
+    if (maxAge != null && maxAge <= 0) {
+      delete cookies[name];
+      return;
+    }
+    if (expires != null && expires.getTime() <= Date.now()) {
+      delete cookies[name];
+      return;
+    }
+    cookies[name] = value;
   });
   Object.entries(cookies).forEach(([key, value]) => {
     headers.append("cookie", `${key}=${value}`);
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index fd417aa00..1e81ea679 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -99,6 +99,9 @@ importers:
       '@vinxi/server-components':
         specifier: ^0.5.0
         version: 0.5.0(vinxi@0.5.7(@types/node@24.3.0)(better-sqlite3@11.8.1)(db0@0.3.2(better-sqlite3@11.8.1)(drizzle-orm@0.31.4(@opentelemetry/api@1.9.0)(@prisma/client@5.22.0(prisma@5.22.0))(@types/better-sqlite3@7.6.12)(better-sqlite3@11.8.1)(prisma@5.22.0)))(drizzle-orm@0.31.4(@opentelemetry/api@1.9.0)(@prisma/client@5.22.0(prisma@5.22.0))(@types/better-sqlite3@7.6.12)(better-sqlite3@11.8.1)(prisma@5.22.0))(ioredis@5.6.1)(jiti@2.4.2)(lightningcss@1.27.0)(terser@5.43.1)(tsx@4.19.2)(yaml@2.6.0))
+      cookie-es:
+        specifier: ^2.0.0
+        version: 2.0.0
       defu:
         specifier: ^6.1.2
         version: 6.1.4
@@ -8218,7 +8221,7 @@ snapshots:
       '@babel/preset-env': 7.26.0(@babel/core@7.26.9)
       babel-loader: 9.2.1(@babel/core@7.26.9)(webpack@5.97.1)
       bluebird: 3.7.1
-      debug: 4.4.0
+      debug: 4.4.1
       lodash: 4.17.21
       webpack: 5.97.1
     transitivePeerDependencies:
@@ -11810,7 +11813,7 @@ snapshots:
 
   istanbul-lib-instrument@4.0.3:
     dependencies:
-      '@babel/core': 7.26.9
+      '@babel/core': 7.27.4
       '@istanbuljs/schema': 0.1.3
       istanbul-lib-coverage: 3.2.2
       semver: 6.3.1
@@ -11834,7 +11837,7 @@ snapshots:
 
   istanbul-lib-source-maps@4.0.1:
     dependencies:
-      debug: 4.4.0
+      debug: 4.4.1
       istanbul-lib-coverage: 3.2.2
       source-map: 0.6.1
     transitivePeerDependencies:
@@ -12145,7 +12148,7 @@ snapshots:
 
   make-dir@4.0.0:
     dependencies:
-      semver: 7.7.1
+      semver: 7.7.2
 
   math-intrinsics@1.1.0: {}