CVE-2021-46823

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.

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.

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 3.3.1 and earlier 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 3.4.0 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 of backslashes in schemas. More than a dozen backslashes per line are atypical.

References

CWE-1333

For more information

If you have any questions or comments about this advisory:

• Open an issue in python-ldap tracker

python-ldap provides an object-oriented API for working with LDAP within Python programs. It allows access to LDAP directory servers by wrapping the OpenLDAP 2.x libraries, and contains modules for other LDAP-related tasks (including processing LDIF, LDAPURLs, LDAPv3 schema, etc.).

Security Fix(es):

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.(CVE-2021-46823)

python-ldap provides an object-oriented API for working with LDAP within Python programs. It allows access to LDAP directory servers by wrapping the OpenLDAP 2.x libraries, and contains modules for other LDAP-related tasks (including processing LDIF, LDAPURLs, LDAPv3 schema, etc.).

Security Fix(es):

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.(CVE-2021-46823)

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.

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.

It was discovered that Python LDAP incorrectly handled certain regular expressions. A remote attacker could possibly use this issue to cause a denial of service (CVE-2021-46823).

It was discovered that Python LDAP incorrectly handled certain regular expressions. An remote attacker could possibly use this issue to cause a denial of service.