From d655030770081e2dfe46f90e27620472a502289d Mon Sep 17 00:00:00 2001
From: David Lord <davidism@gmail.com>
Date: Thu, 2 May 2024 09:14:00 -0700
Subject: [PATCH] disallow invalid characters in keys to xmlattr filter

---
 CHANGES.rst           |  6 ++++++
 src/jinja2/filters.py | 22 +++++++++++++++++-----
 tests/test_filters.py | 11 ++++++-----
 3 files changed, 29 insertions(+), 10 deletions(-)

Index: Jinja2-3.1.2/CHANGES.rst
===================================================================
--- Jinja2-3.1.2.orig/CHANGES.rst
+++ Jinja2-3.1.2/CHANGES.rst
@@ -9,6 +9,12 @@ Released 2022-04-28
     :issue:`1645`
 -   Handle race condition in ``FileSystemBytecodeCache``. :issue:`1654`
 
+-   The ``xmlattr`` filter does not allow keys with ``/`` solidus, ``>``
+    greater-than sign, or ``=`` equals sign, in addition to disallowing spaces.
+    Regardless of any validation done by Jinja, user input should never be used
+    as keys to this filter, or must be separately validated first.
+    GHSA-h75v-3vvj-5mfj
+
 
 Version 3.1.1
 -------------
Index: Jinja2-3.1.2/src/jinja2/filters.py
===================================================================
--- Jinja2-3.1.2.orig/src/jinja2/filters.py
+++ Jinja2-3.1.2/src/jinja2/filters.py
@@ -248,13 +248,25 @@ def do_items(value: t.Union[t.Mapping[K,
     yield from value.items()
 
 
+# Check for characters that would move the parser state from key to value.
+# https://html.spec.whatwg.org/#attribute-name-state
+_attr_key_re = re.compile(r"[\s/>=]", flags=re.ASCII)
+
+
 @pass_eval_context
 def do_xmlattr(
     eval_ctx: "EvalContext", d: t.Mapping[str, t.Any], autospace: bool = True
 ) -> str:
     """Create an SGML/XML attribute string based on the items in a dict.
-    All values that are neither `none` nor `undefined` are automatically
-    escaped:
+
+    **Values** that are neither ``none`` nor ``undefined`` are automatically
+    escaped, safely allowing untrusted user input.
+
+    User input should not be used as **keys** to this filter. If any key
+    contains a space, ``/`` solidus, ``>`` greater-than sign, or ``=`` equals
+    sign, this fails with a ``ValueError``. Regardless of this, user input
+    should never be used as keys to this filter, or must be separately validated
+    first.
 
     .. sourcecode:: html+jinja
 
@@ -273,12 +285,23 @@ def do_xmlattr(
 
     As you can see it automatically prepends a space in front of the item
     if the filter returned something unless the second parameter is false.
+
+    Keys with ``/`` solidus, ``>`` greater-than sign, or ``=`` equals sign
+    are not allowed.
+
+    Keys with spaces are not allowed.
     """
-    rv = " ".join(
-        f'{escape(key)}="{escape(value)}"'
-        for key, value in d.items()
-        if value is not None and not isinstance(value, Undefined)
-    )
+    items = []
+    for key, value in d.items():
+        if value is None or isinstance(value, Undefined):
+            continue
+
+        if _attr_key_re.search(key) is not None:
+            raise ValueError("Invalid character in attribute name: {key!r}")
+
+        items.append(f'{escape(key)}="{escape(value)}"')
+
+    rv = " ".join(items)
 
     if autospace and rv:
         rv = " " + rv
Index: Jinja2-3.1.2/tests/test_filters.py
===================================================================
--- Jinja2-3.1.2.orig/tests/test_filters.py
+++ Jinja2-3.1.2/tests/test_filters.py
@@ -871,3 +871,10 @@ class TestFilter:
         with pytest.raises(TemplateRuntimeError, match="No filter named 'f'"):
             t1.render(x=42)
             t2.render(x=42)
+
+    @pytest.mark.parametrize("sep", ("\t", "\n", "\f", " ", "/", ">", "="))
+    def test_xmlattr_key_invalid(self, env: Environment, sep: str) -> None:
+        with pytest.raises(ValueError, match="Invalid character"):
+            env.from_string("{{ {key: 'my_class'}|xmlattr }}").render(
+                key=f"class{sep}onclick=alert(1)"
+            )