diff -up firefox-68.2.0/security/manager/ssl/nsNSSComponent.cpp.old firefox-68.2.0/security/manager/ssl/nsNSSComponent.cpp

--- firefox-68.2.0/security/manager/ssl/nsNSSComponent.cpp.old	2019-10-24 14:20:21.227037984 +0200

+++ firefox-68.2.0/security/manager/ssl/nsNSSComponent.cpp	2019-10-24 14:45:52.769506967 +0200

@@ -996,6 +996,9 @@ void nsNSSComponent::FillTLSVersionRange

     return;

   }

+  // Enable TLS 1.3 as our NSS supports it.

+  supported.max = 0x304;

+

   // Clip the defaults by what NSS actually supports to enable

   // working with a system NSS with different ranges.

   rangeOut.min = std::max(rangeOut.min, supported.min);