diff --git a/pkgs/development/compilers/cudatoolkit/versions.toml b/pkgs/development/compilers/cudatoolkit/versions.toml
index 5628c323d529..46173cca12cd 100644
--- a/pkgs/development/compilers/cudatoolkit/versions.toml
+++ b/pkgs/development/compilers/cudatoolkit/versions.toml
@@ -44,13 +44,15 @@ gcc = "gcc9"
 version = "11.4.2"
 url = "https://developer.download.nvidia.com/compute/cuda/11.4.2/local_installers/cuda_11.4.2_470.57.02_linux.run"
 sha256 = "sha256-u9h8oOkT+DdFSnljZ0c1E83e9VUILk2G7Zo4ZZzIHwo="
-gcc = "gcc11"
+gcc = "gcc10"
 
 ["11.5"]
 version = "11.5.0"
 url = "https://developer.download.nvidia.com/compute/cuda/11.5.0/local_installers/cuda_11.5.0_495.29.05_linux.run"
 sha256 = "sha256-rgoWk9lJfPPYHmlIlD43lGNpANtxyY1Y7v2sr38aHkw="
-gcc = "gcc11"
+# cuda 11.5 has problems with glibc 2.4 -> keeping gcc10
+# cf. https://forums.developer.nvidia.com/t/cuda-11-5-samples-throw-multiple-error-attribute-malloc-does-not-take-arguments/192750/15
+gcc = "gcc10"
 
 ["11.6"]
 version = "11.6.1"
diff --git a/pkgs/development/libraries/science/math/nccl/default.nix b/pkgs/development/libraries/science/math/nccl/default.nix
index c08b5aa5851d..41dddf2391ac 100644
--- a/pkgs/development/libraries/science/math/nccl/default.nix
+++ b/pkgs/development/libraries/science/math/nccl/default.nix
@@ -2,13 +2,13 @@
 
 stdenv.mkDerivation rec {
   name = "nccl-${version}-cuda-${cudatoolkit.majorVersion}";
-  version = "2.7.8-1";
+  version = "2.12.10-1";
 
   src = fetchFromGitHub {
     owner = "NVIDIA";
     repo = "nccl";
     rev = "v${version}";
-    sha256 = "0xxiwaw239dc9g015fka3k1nvm5zyl00dzgxnwzkang61dys9wln";
+    sha256 = "sha256-QqORzm0gD+QG+P8rId8bQn2oZsxL5YyxCIobUVs85wE=";
   };
 
   outputs = [ "out" "dev" ];
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 7ff59deceecb..1cfa868fa4b8 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -3584,7 +3584,6 @@ with pkgs;
   gpu-burn = callPackage ../applications/misc/gpu-burn {
     # gpu-burn doesn't build on gcc11. CUDA 11.3 is the last version to use
     # pre-gcc11, in particular gcc9.
-    cudatoolkit = cudaPackages_11_3.cudatoolkit;
     stdenv = gcc9Stdenv;
   };
 
@@ -4884,7 +4883,7 @@ with pkgs;
   cudaPackages_11_4 = callPackage ./cuda-packages.nix { cudaVersion = "11.4"; };
   cudaPackages_11_5 = callPackage ./cuda-packages.nix { cudaVersion = "11.5"; };
   cudaPackages_11_6 = callPackage ./cuda-packages.nix { cudaVersion = "11.6"; };
-  cudaPackages_11 = cudaPackages_11_5;
+  cudaPackages_11 = cudaPackages_11_6;
   cudaPackages = recurseIntoAttrs cudaPackages_11;
 
   # TODO: move to alias
@@ -23114,7 +23113,6 @@ with pkgs;
     cudaSupport = true;
     # librealsenseWithCuda doesn't build on gcc11. CUDA 11.3 is the last version
     # to use pre-gcc11, in particular gcc9.
-    cudaPackages = cudaPackages_11_3;
     stdenv = gcc9Stdenv;
   };
 
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index 489a250ba5e4..4cbede6e070e 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -1958,11 +1958,7 @@ in {
 
   cufflinks = callPackage ../development/python-modules/cufflinks { };
 
-  cupy = callPackage ../development/python-modules/cupy {
-    # cupy doesn't build on gcc11. CUDA 11.3 is the last version to use
-    # pre-gcc11, in particular gcc9.
-    cudaPackages = pkgs.cudaPackages_11_3;
-  };
+  cupy = callPackage ../development/python-modules/cupy { };
 
   curio = callPackage ../development/python-modules/curio { };