ldap.dn.escape_dn_chars() escapes \x00 incorrectly by emitting a backslash followed by a literal NUL byte instead of the RFC-4514 hex form \00. Any application that uses this helper to construct DNs from untrusted input can be made to consistently fail before a request is sent to the LDAP server (e.g., AD), resulting in a client-side denial of service.
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.
python-ldap before 3.4.0 is vulnerable to a denial of service when ldap.schema is used for untrusted schema definitions, because of a regular expression denial of service (ReDoS) flaw in the LDAP schema parser. By sending crafted regex input, a remote authenticated attacker could exploit this vulnerability to cause a denial of service condition.
https://github.com/python-ldap/python-ldap/issues/424 Impact The LDAP schema parser of python-ldap are vulnerable to a regular expression denial-of-service attack. The issue affects clients that use ldap.schema package to parse LDAP schema definitions from an untrusted source. Patches The upcoming release of python-ldap will contain a workaround to prevent ReDoS attacks. The schema parser refuses schema definitions with an excessive amount of backslashes. Workarounds As a workaround, users can check input for excessive amount …