diff --git a/pkgs/applications/networking/browsers/firefox/packages.nix b/pkgs/applications/networking/browsers/firefox/packages.nix
index 0032e607ec8..7903a345e1f 100644
--- a/pkgs/applications/networking/browsers/firefox/packages.nix
+++ b/pkgs/applications/networking/browsers/firefox/packages.nix
@@ -89,6 +89,7 @@ rec {
 
     meta = firefox.meta // {
       description = "A web browser built from Firefox Extended Support Release source tree";
+      knownVulnerabilities = [ "Support ended around October 2019." ];
     };
     updateScript = callPackage ./update.nix {
       attrPath = "firefox-esr-60-unwrapped";