diff --git a/setuptools/package_index.py b/setuptools/package_index.py
index b6407be..bdcf4a6 100755
--- a/setuptools/package_index.py
+++ b/setuptools/package_index.py
@@ -212,7 +212,7 @@ def unique_values(func):
     return wrapper
 
 
-REL = re.compile(r"""<([^>]*\srel\s*=\s*['"]?([^'">]+)[^>]*)>""", re.I)
+REL = re.compile(r"""<([^>]*\srel\s{0,10}=\s{0,10}['"]?([^'" >]+)[^>]*)>""", re.I)
 # this line is here to fix emacs' cruddy broken syntax highlighting
 
 
diff --git a/setuptools/tests/test_packageindex.py b/setuptools/tests/test_packageindex.py
index 63b9294..49bd819 100644
--- a/setuptools/tests/test_packageindex.py
+++ b/setuptools/tests/test_packageindex.py
@@ -223,6 +223,12 @@ class TestPackageIndex:
             assert dists[0].version == ''
             assert dists[1].version == vc
 
+    def test_REL_DoS(self):
+        """
+        REL should not hang on a contrived attack string.
+        """
+        setuptools.package_index.REL.search('< rel=' + ' ' * 2**12)
+
 
 class TestContentCheckers:
     def test_md5(self):