validate samesite attribute in ResponseCookie

spring-web/src/main/java/org/springframework/http/ResponseCookie.java

@@ -75,6 +75,7 @@ private ResponseCookie(String name, @Nullable String value, Duration maxAge, @Nu
 		Rfc6265Utils.validateCookieValue(value);
 		Rfc6265Utils.validateDomain(domain);
 		Rfc6265Utils.validatePath(path);
+		Rfc6265Utils.validateSameSite(sameSite);
 	}
 
 
@@ -433,6 +434,18 @@ public static void validatePath(@Nullable String path) {
 				}
 			}
 		}
+
+		public static void validateSameSite(@Nullable String sameSite) {
+			if (sameSite == null) {
+				return;
+			}
+			for (int i = 0; i < sameSite.length(); i++) {
+				char c = sameSite.charAt(i);
+				if (c < 0x20 || c > 0x7E || c == ';') {
+					throw new IllegalArgumentException(sameSite + ": Invalid cookie SameSite char '" + c + "'");
+				}
+			}
+		}
 	}
 
 

spring-web/src/test/java/org/springframework/http/ResponseCookieTests.java

@@ -82,6 +82,17 @@ void domainChecks() {
 						.hasMessageContaining("invalid cookie domain char"));
 	}
 
+	@Test
+	void sameSiteChecks() {
+
+		Arrays.asList("Strict", "Lax", "None")
+				.forEach(sameSite -> ResponseCookie.from("n", "v").sameSite(sameSite).build());
+
+		Arrays.asList("Lax\r\nSet-Cookie: x=y", "Lax\n", "La;x", "Lax\t", "Lax\u0005")
+				.forEach(sameSite -> assertThatThrownBy(() -> ResponseCookie.from("n", "v").sameSite(sameSite).build())
+						.hasMessageContaining("Invalid cookie SameSite char"));
+	}
+
 	@Test // gh-24663
 	void domainWithEmptyDoubleQuotes() {