diff --git a/app/common/src/main/java/stirling/software/common/model/MultipartFile.java b/app/common/src/main/java/stirling/software/common/model/MultipartFile.java
index eb20c92ddf..0e1cd4966a 100644
--- a/app/common/src/main/java/stirling/software/common/model/MultipartFile.java
+++ b/app/common/src/main/java/stirling/software/common/model/MultipartFile.java
@@ -60,7 +60,8 @@ public interface MultipartFile {
 
     default void transferTo(Path dest) throws IOException {
         try (InputStream in = getInputStream()) {
-            // Spring's MultipartFile#transferTo overwrites an existing destination. Callers commonly
+            // Spring's MultipartFile#transferTo overwrites an existing destination. Callers
+            // commonly
             // pass a path from Files.createTempFile(...) (which has already created an empty file),
             // so REPLACE_EXISTING is required - a plain Files.copy would throw FileAlreadyExists.
             Files.copy(in, dest, java.nio.file.StandardCopyOption.REPLACE_EXISTING);
diff --git a/app/proprietary/src/main/java/stirling/software/proprietary/security/oauth2/OAuth2CallbackServlet.java b/app/proprietary/src/main/java/stirling/software/proprietary/security/oauth2/OAuth2CallbackServlet.java
index 6737cf73cd..52a04d3d43 100644
--- a/app/proprietary/src/main/java/stirling/software/proprietary/security/oauth2/OAuth2CallbackServlet.java
+++ b/app/proprietary/src/main/java/stirling/software/proprietary/security/oauth2/OAuth2CallbackServlet.java
@@ -111,10 +111,7 @@ public class OAuth2CallbackServlet extends HttpServlet {
                             Map.of(
                                     "authType", AuthenticationType.OAUTH2.toString(),
                                     "role", user.getRolesAsString()));
-            Cookie cookie = new Cookie("stirling_jwt", jwt);
-            cookie.setPath("/");
-            cookie.setHttpOnly(true);
-            response.addCookie(cookie);
+            response.addCookie(jwtCookie(jwt, request));
             response.sendRedirect(baseUrl(request) + "/");
         } catch (Exception e) {
             log.error("OAuth2 callback failed", e);
@@ -203,6 +200,17 @@ public class OAuth2CallbackServlet extends HttpServlet {
         return baseUrl(request) + "/login/oauth2/code/" + REG_ID;
     }
 
+    private Cookie jwtCookie(String jwt, HttpServletRequest request) {
+        Cookie cookie = new Cookie("stirling_jwt", jwt);
+        cookie.setPath("/");
+        cookie.setHttpOnly(true);
+        // Secure when the request arrived over HTTPS (production); left off for the http localhost
+        // test deployments so the SSO cookie round-trips there.
+        cookie.setSecure(request.isSecure());
+        cookie.setAttribute("SameSite", "Lax");
+        return cookie;
+    }
+
     private String baseUrl(HttpServletRequest request) {
         String backendUrl = applicationProperties.getSystem().getBackendUrl();
         if (backendUrl != null && !backendUrl.isBlank()) {
diff --git a/app/proprietary/src/main/java/stirling/software/proprietary/security/saml2/SamlSpServlet.java b/app/proprietary/src/main/java/stirling/software/proprietary/security/saml2/SamlSpServlet.java
index f10d5b81b5..3faa773691 100644
--- a/app/proprietary/src/main/java/stirling/software/proprietary/security/saml2/SamlSpServlet.java
+++ b/app/proprietary/src/main/java/stirling/software/proprietary/security/saml2/SamlSpServlet.java
@@ -81,10 +81,7 @@ public class SamlSpServlet extends HttpServlet {
                             Map.of(
                                     "authType", AuthenticationType.SSO.toString(),
                                     "role", user.getRolesAsString()));
-            Cookie cookie = new Cookie("stirling_jwt", jwt);
-            cookie.setPath("/");
-            cookie.setHttpOnly(true);
-            response.addCookie(cookie);
+            response.addCookie(jwtCookie(jwt, request));
             response.sendRedirect(baseUrl(request) + "/");
         } catch (Exception e) {
             log.error("SAML ACS validation failed", e);
@@ -117,6 +114,17 @@ public class SamlSpServlet extends HttpServlet {
         }
     }
 
+    private Cookie jwtCookie(String jwt, HttpServletRequest request) {
+        Cookie cookie = new Cookie("stirling_jwt", jwt);
+        cookie.setPath("/");
+        cookie.setHttpOnly(true);
+        // Secure when the request arrived over HTTPS (production); left off for the http localhost
+        // test deployments so the SSO cookie round-trips there.
+        cookie.setSecure(request.isSecure());
+        cookie.setAttribute("SameSite", "Lax");
+        return cookie;
+    }
+
     private String baseUrl(HttpServletRequest request) {
         String backendUrl = applicationProperties.getSystem().getBackendUrl();
         if (backendUrl != null && !backendUrl.isBlank()) {