CVE-2026-11526

@@ -101,9 +101,10 @@ sub _make_filehandle {
   }
   return $fh if defined(fileno $fh);
 
-  # otherwise treat it as a file to open
+  # otherwise treat it as a file to open; 3-arg open so the filename is
+  # not interpreted as a command or redirect
   $fh = gensym;
-  if (!open($fh,$thing)) {
+  if (!open($fh,'<',$thing)) {
     die "$thing not found: $!";
     return undef;
   }

@@ -129,9 +129,10 @@ sub _make_filehandle {
   }
   return $fh if defined(fileno $fh);
 
-  # otherwise treat it as a file to open
+  # otherwise treat it as a file to open; 3-arg open so the filename is
+  # not interpreted as a command or redirect
   $fh = gensym;
-  if (!open($fh,$thing)) {
+  if (!open($fh,'<',$thing)) {
     die "$thing not found: $!";
     return undef;
   }

@@ -40,6 +40,7 @@ t/Polyline.t
 t/autodetect.t
 t/caller.t
 t/fork.t
+t/security_open.t
 t/test_data/Generic.ttf
 t/test_data/frog.jpg
 t/test_data/frog.xbm

@@ -0,0 +1,61 @@
+# _make_filehandle is the single open path for every filename constructor
+# (new, newFrom*). A 2-arg open() there interprets shell-magic prefixes, so a
+# "cmd |" filename runs a command and a "> file" filename truncates a file.
+# These must be treated as plain pathnames.
+use strict;
+use warnings;
+use GD;
+use File::Temp qw( tempdir );
+use File::Spec;
+use Test::More tests => 5;
+
+my $dir = tempdir(CLEANUP => 1);
+
+# A trailing-pipe payload must not run a command.
+{
+  my $marker = File::Spec->catfile($dir, "pwned_read");
+  my $fh     = eval { GD::Image->_make_filehandle("touch $marker |") };
+  close $fh if $fh;
+  ok !-e $marker, "trailing-pipe payload does not execute a command";
+}
+
+# A leading-pipe payload must not run a command.
+{
+  my $marker = File::Spec->catfile($dir, "pwned_write");
+  my $fh     = eval { GD::Image->_make_filehandle("| touch $marker") };
+  close $fh if $fh;
+  ok !-e $marker, "leading-pipe payload does not execute a command";
+}
+
+# A redirect payload must not truncate a file.
+{
+  my $victim = File::Spec->catfile($dir, "victim");
+  open my $fh, ">", $victim or die "$victim: $!";
+  print $fh "important data\n";
+  close $fh;
+  my $made = eval { GD::Image->_make_filehandle("> $victim") };
+  close $made if $made;
+  is -s $victim, 15, "redirect payload does not truncate a file";
+}
+
+# A plain filename still opens as a file.
+{
+  my $real = File::Spec->catfile($dir, "real.txt");
+  open my $fh, ">", $real or die "$real: $!";
+  print $fh "x\n";
+  close $fh;
+  my $opened = eval { GD::Image->_make_filehandle($real) };
+  ok $opened, "plain filename still opens as a file";
+}
+
+# 2-arg open() silently trimmed surrounding whitespace (including a trailing
+# newline); 3-arg open treats the argument literally, so an un-chomped name no
+# longer opens the trimmed file.
+{
+  my $real = File::Spec->catfile($dir, "plain.txt");
+  open my $fh, ">", $real or die "$real: $!";
+  print $fh "x\n";
+  close $fh;
+  my $padded = eval { GD::Image->_make_filehandle("$real\n") };
+  ok !$padded, "trailing whitespace is significant (filename not trimmed)";
+}