diff --git a/pkgs/by-name/gn/gnutar/acl-2.4.0-name-conflicts.patch b/pkgs/by-name/gn/gnutar/acl-2.4.0-name-conflicts.patch
new file mode 100644
index 000000000000..c871551bc772
--- /dev/null
+++ b/pkgs/by-name/gn/gnutar/acl-2.4.0-name-conflicts.patch
@@ -0,0 +1,85 @@
+diff --git a/src/xattrs.c b/src/xattrs.c
+index 86a7e59cbc..c872ae308d 100644
+--- a/src/xattrs.c
++++ b/src/xattrs.c
+@@ -139,13 +139,13 @@
+ #ifdef HAVE_POSIX_ACLS
+ 
+ /* acl-at wrappers, TODO: move to gnulib in future? */
+-static acl_t acl_get_file_at (int, const char *, acl_type_t);
+-static int acl_set_file_at (int, const char *, acl_type_t, acl_t);
++static acl_t tar_acl_get_file_at (int, const char *, acl_type_t);
++static int tar_acl_set_file_at (int, const char *, acl_type_t, acl_t);
+ static int file_has_acl_at (int, char const *, struct stat const *);
+-static int acl_delete_def_file_at (int, char const *);
++static int tar_acl_delete_def_file_at (int, char const *);
+ 
+-/* acl_get_file_at */
+-#define AT_FUNC_NAME acl_get_file_at
++/* tar_acl_get_file_at */
++#define AT_FUNC_NAME tar_acl_get_file_at
+ #define AT_FUNC_RESULT acl_t
+ #define AT_FUNC_FAIL (acl_t)NULL
+ #define AT_FUNC_F1 acl_get_file
+@@ -159,8 +159,8 @@
+ #undef AT_FUNC_POST_FILE_PARAM_DECLS
+ #undef AT_FUNC_POST_FILE_ARGS
+ 
+-/* acl_set_file_at */
+-#define AT_FUNC_NAME acl_set_file_at
++/* tar_acl_set_file_at */
++#define AT_FUNC_NAME tar_acl_set_file_at
+ #define AT_FUNC_F1 acl_set_file
+ #define AT_FUNC_POST_FILE_PARAM_DECLS   , acl_type_t type, acl_t acl
+ #define AT_FUNC_POST_FILE_ARGS          , type, acl
+@@ -170,8 +170,8 @@
+ #undef AT_FUNC_POST_FILE_PARAM_DECLS
+ #undef AT_FUNC_POST_FILE_ARGS
+ 
+-/* acl_delete_def_file_at */
+-#define AT_FUNC_NAME acl_delete_def_file_at
++/* tar_acl_delete_def_file_at */
++#define AT_FUNC_NAME tar_acl_delete_def_file_at
+ #define AT_FUNC_F1 acl_delete_def_file
+ #define AT_FUNC_POST_FILE_PARAM_DECLS
+ #define AT_FUNC_POST_FILE_ARGS
+@@ -299,10 +299,10 @@
+       /* No "default" IEEE 1003.1e ACL set for directory.  At this moment,
+          FILE_NAME may already have inherited default acls from parent
+          directory;  clean them up. */
+-      if (acl_delete_def_file_at (chdir_fd, file_name))
++      if (tar_acl_delete_def_file_at (chdir_fd, file_name))
+         WARNOPT (WARN_XATTR_WRITE,
+                 (0, errno,
+-                 _("acl_delete_def_file_at: Cannot drop default POSIX ACLs "
++                 _("tar_acl_delete_def_file_at: Cannot drop default POSIX ACLs "
+                    "for file '%s'"),
+                  file_name));
+       return;
+@@ -316,11 +316,11 @@
+       return;
+     }
+ 
+-  if (acl_set_file_at (chdir_fd, file_name, type, acl) == -1)
++  if (tar_acl_set_file_at (chdir_fd, file_name, type, acl) == -1)
+     /* warn even if filesystem does not support acls */
+     WARNOPT (WARN_XATTR_WRITE,
+ 	     (0, errno,
+-	      _ ("acl_set_file_at: Cannot set POSIX ACLs for file '%s'"),
++	      _ ("tar_acl_set_file_at: Cannot set POSIX ACLs for file '%s'"),
+ 	      file_name));
+ 
+   acl_free (acl);
+@@ -357,10 +357,10 @@
+   char *val = NULL;
+   acl_t acl;
+ 
+-  if (!(acl = acl_get_file_at (parentfd, file_name, type)))
++  if (!(acl = tar_acl_get_file_at (parentfd, file_name, type)))
+     {
+       if (errno != ENOTSUP)
+-        call_arg_warn ("acl_get_file_at", file_name);
++        call_arg_warn ("tar_acl_get_file_at", file_name);
+       return;
+     }
+ 
diff --git a/pkgs/by-name/gn/gnutar/package.nix b/pkgs/by-name/gn/gnutar/package.nix
index acf5f3233aeb..c7b072b71d10 100644
--- a/pkgs/by-name/gn/gnutar/package.nix
+++ b/pkgs/by-name/gn/gnutar/package.nix
@@ -24,9 +24,17 @@ stdenv.mkDerivation (finalAttrs: {
     sha256 = "sha256-TWL/NzQux67XSFNTI5MMfPlKz3HDWRiCsmp+pQ8+3BY=";
   };
 
-  # GNU tar fails to link libiconv even though the configure script detects it.
-  # https://savannah.gnu.org/bugs/index.php?64441
-  patches = [ ./link-libiconv.patch ];
+  patches = [
+    # GNU tar fails to link libiconv even though the configure script detects it.
+    # https://savannah.gnu.org/bugs/index.php?64441
+    ./link-libiconv.patch
+
+    # acl 2.4.0 adds functions that have name conflicts with internal
+    # (`static`) functions from GNU tar. we prefix `tar_` to these names to
+    # avoid this, matching the approach from
+    # https://lists.gnu.org/archive/html/bug-tar/2026-06/msg00013.html
+    ./acl-2.4.0-name-conflicts.patch
+  ];
 
   # gnutar tries to call into gettext between `fork` and `exec`,
   # which is not safe on darwin.
diff --git a/pkgs/development/libraries/acl/default.nix b/pkgs/development/libraries/acl/default.nix
index 3397e6e27a14..75934d780a90 100644
--- a/pkgs/development/libraries/acl/default.nix
+++ b/pkgs/development/libraries/acl/default.nix
@@ -13,11 +13,11 @@
 
 stdenv.mkDerivation (finalAttrs: {
   pname = "acl";
-  version = "2.3.2";
+  version = "2.4.0";
 
   src = fetchurl {
     url = "mirror://savannah/acl/acl-${finalAttrs.version}.tar.gz";
-    hash = "sha256-XyvbrWKXB6p9hcYj+ZSqih0t7FWnPeUgW6wL9gWKL3w=";
+    hash = "sha256-c8hTw9ROH2k+WpaphvG9GdPQ2sLH1FPnlhd3dLxOX2o=";
   };
 
   outputs = [