diff --git a/nixos/modules/services/misc/jellyfin.nix b/nixos/modules/services/misc/jellyfin.nix
index 64b774a220b6..c1b45864041b 100644
--- a/nixos/modules/services/misc/jellyfin.nix
+++ b/nixos/modules/services/misc/jellyfin.nix
@@ -18,6 +18,7 @@ in
 
       package = mkOption {
         type = types.package;
+        default = pkgs.jellyfin;
         example = literalExample "pkgs.jellyfin";
         description = ''
           Jellyfin package to use.
@@ -98,11 +99,6 @@ in
       };
     };
 
-    services.jellyfin.package = mkDefault (
-      if versionAtLeast config.system.stateVersion "20.09" then pkgs.jellyfin
-        else pkgs.jellyfin_10_5
-    );
-
     users.users = mkIf (cfg.user == "jellyfin") {
       jellyfin = {
         group = cfg.group;
diff --git a/pkgs/servers/jellyfin/10.5.x.nix b/pkgs/servers/jellyfin/10.5.x.nix
deleted file mode 100644
index 9bece72566f8..000000000000
--- a/pkgs/servers/jellyfin/10.5.x.nix
+++ /dev/null
@@ -1,61 +0,0 @@
-{ stdenv, lib, fetchurl, unzip, sqlite, makeWrapper, dotnetCorePackages, ffmpeg,
-  fontconfig, freetype, nixosTests }:
-
-let
-  os = if stdenv.isDarwin then "osx" else "linux";
-  arch =
-    with stdenv.hostPlatform;
-    if isx86_32 then "x86"
-    else if isx86_64 then "x64"
-    else if isAarch32 then "arm"
-    else if isAarch64 then "arm64"
-    else lib.warn "Unsupported architecture, some image processing features might be unavailable" "unknown";
-  musl = lib.optionalString stdenv.hostPlatform.isMusl
-    (if (arch != "x64")
-      then lib.warn "Some image processing features might be unavailable for non x86-64 with Musl" "musl-"
-      else "musl-");
-  runtimeDir = "${os}-${musl}${arch}";
-
-in stdenv.mkDerivation rec {
-  pname = "jellyfin";
-  version = "10.5.5";
-
-  # Impossible to build anything offline with dotnet
-  src = fetchurl {
-    url = "https://github.com/jellyfin/jellyfin/releases/download/v${version}/jellyfin_${version}_portable.tar.gz";
-    sha256 = "1s3hva1j5w74qc9wyqnmr5clk4smzfi7wvx8qrzrwy81mx7r5w27";
-  };
-
-  nativeBuildInputs = [ unzip ];
-  buildInputs = [
-    makeWrapper
-  ];
-
-  propagatedBuildInputs = [
-    dotnetCorePackages.aspnetcore_3_1
-    sqlite
-  ];
-
-  preferLocalBuild = true;
-
-  installPhase = ''
-    install -dm 755 "$out/opt/jellyfin"
-    cp -r * "$out/opt/jellyfin"
-    makeWrapper "${dotnetCorePackages.aspnetcore_3_1}/bin/dotnet" $out/bin/jellyfin \
-      --prefix LD_LIBRARY_PATH : "${lib.makeLibraryPath [
-        sqlite fontconfig freetype stdenv.cc.cc.lib
-      ]}:$out/opt/jellyfin/runtimes/${runtimeDir}/native/" \
-      --add-flags "$out/opt/jellyfin/jellyfin.dll --ffmpeg ${ffmpeg}/bin/ffmpeg"
-  '';
-
-  passthru.tests = {
-    smoke-test = nixosTests.jellyfin;
-  };
-
-  meta =  with lib; {
-    description = "The Free Software Media System";
-    homepage = "https://jellyfin.org/";
-    license = licenses.gpl2;
-    maintainers = with maintainers; [ nyanloutre minijackson ];
-  };
-}
diff --git a/pkgs/top-level/aliases.nix b/pkgs/top-level/aliases.nix
index d7f1fff525d6..8f2ff5cc4f72 100644
--- a/pkgs/top-level/aliases.nix
+++ b/pkgs/top-level/aliases.nix
@@ -336,6 +336,7 @@ mapAliases ({
   kodiGBM = kodi-gbm;
   kodiPlain = kodi;
   kodiPlainWayland = kodi-wayland;
+  jellyfin_10_5 = throw "Jellyfin 10.5 is no longer supported and contains a security vulnerability. Please upgrade to a newer version."; # added 2021-04-26
   julia_07 = throw "julia_07 is deprecated in favor of julia_10 LTS"; # added 2020-09-15
   julia_11 = throw "julia_11 is deprecated in favor of latest Julia version"; # added 2020-09-15
   kdeconnect = plasma5Packages.kdeconnect-kde; # added 2020-10-28
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index fcfa0b51d852..622554efd8e3 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -2697,8 +2697,6 @@ in
 
   jellyfin = callPackage ../servers/jellyfin { };
 
-  jellyfin_10_5 = callPackage ../servers/jellyfin/10.5.x.nix { };
-
   jellyfin-media-player = libsForQt5.callPackage ../applications/video/jellyfin-media-player {
     inherit (darwin.apple_sdk.frameworks) CoreFoundation Cocoa CoreAudio MediaPlayer;
   };