Headline
CVE-2023-40587: fix: reject NUL character as path element · Pylons/pyramid@347d775
Pyramid is an open source Python web framework. A path traversal vulnerability in Pyramid versions 2.0.0 and 2.0.1 impacts users of Python 3.11 that are using a Pyramid static view with a full filesystem path and have a index.html file that is located exactly one directory above the location of the static view’s file system path. No further path traversal exists, and the only file that could be disclosed accidentally is index.html. Pyramid version 2.0.2 rejects any path that contains a null-byte out of caution. While valid in directory/file names, we would strongly consider it a mistake to use null-bytes in naming files/directories. Secondly, Python 3.11, and 3.12 has fixed the underlying issue in os.path.normpath to no longer truncate on the first 0x00 found, returning the behavior to pre-3.11 Python, un an as of yet unreleased version. Fixes will be available in:Python 3.12.0rc2 and 3.11.5. Some workarounds are available. Use a version of Python 3 that is not affected, downgrade to Python 3.10 series temporarily, or wait until Python 3.11.5 is released and upgrade to the latest version of Python 3.11 series.
Expand Up @@ -260,12 +260,12 @@ def _add_vary(response, option): response.vary = vary
_seps = {’/’, os.sep} _invalid_element_chars = {’/’, os.sep, '\x00’}
def _contains_slash(item): for sep in _seps: if sep in item: def _contains_invalid_element_char(item): for invalid_element_char in _invalid_element_chars: if invalid_element_char in item: return True
Expand All @@ -279,7 +279,7 @@ def _secure_path(path_tuple): # unless someone screws up the traversal_path code # (request.subpath is computed via traversal_path too) return None if any([_contains_slash(item) for item in path_tuple]): if any([_contains_invalid_element_char(item) for item in path_tuple]): return None encoded = '/’.join(path_tuple) # will be unicode return encoded Expand Down