diff --git a/pkgs/development/libraries/zlog/default.nix b/pkgs/development/libraries/zlog/default.nix
index 99163ae5dc6c..82c08b46bc8b 100644
--- a/pkgs/development/libraries/zlog/default.nix
+++ b/pkgs/development/libraries/zlog/default.nix
@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchFromGitHub }:
+{ lib, stdenv, fetchFromGitHub, fetchpatch }:
 
 stdenv.mkDerivation rec {
   version = "1.2.15";
@@ -11,6 +11,14 @@ stdenv.mkDerivation rec {
     sha256 = "10hzifgpml7jm43y6v8c8q0cr9ziyx9qxznafxyw6glhnlqnb7pb";
   };
 
+  patches = [
+    (fetchpatch {
+      name = "CVE-2021-43521.patch";
+      url = "https://github.com/HardySimpson/zlog/commit/a5be8b3a8ddc498de4ad041757285136a55d97e3.patch";
+      sha256 = "sha256-igHXUHN2Ke8Gb5AeDrDwG2aUNRpispgqVlGuASute+8=";
+    })
+  ];
+
   makeFlags = [ "PREFIX=${placeholder "out"}" ];
 
   meta = with lib; {