diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
index 6814ff6c951..2cd762c75b0 100644
--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -13577,6 +13577,23 @@ nsContentUtils::GetSubresourceCacheValidationInfo(nsIRequest* aRequest,
     if (!info.mMustRevalidate) {
       (void)httpChannel->IsNoCacheResponse(&info.mMustRevalidate);
     }
+
+    if (!info.mMustRevalidate) {
+      nsAutoCString vary;
+      (void)httpChannel->GetResponseHeader("vary"_ns, vary);
+      info.mMustRevalidate = [&] {
+        for (const nsACString& token :
+             nsCCharSeparatedTokenizer(vary, ',').ToRange()) {
+          if (token.EqualsLiteral("*")) {
+            return true;
+          }
+          if (token.EqualsIgnoreCase("cookie")) {
+            return true;
+          }
+        }
+        return false;
+      }();
+    }
   }
 
   // data: URIs are safe to cache across documents under any circumstance, so we