Headline
CVE-2018-1000807: fix a memory leak and a potential UAF and also #722 by reaperhulk · Pull Request #723 · pyca/pyopenssl
Python Cryptographic Authority pyopenssl version prior to version 17.5.0 contains a CWE-416: Use After Free vulnerability in X509 object handling that can result in Use after free can lead to possible denial of service or remote code execution… This attack appear to be exploitable via Depends on the calling application and if it retains a reference to the memory… This vulnerability appears to have been fixed in 17.5.0.
In the callback we were creating an X509 object that didn’t own its own memory so if you retained a reference to it after the callback completed you could end up in a UAF situation.
In PKCS12 we freed the stack but freeing the stack doesn’t free the underlying objects. This meant that any PKCS12 with cacerts was leaking memory every load.
Finally, we clean up one other little area where we can use _from_raw_x509_ptr.
This needs CHANGELOG entries, but it also can’t be merged until we backport pyca/cryptography#4028 and release a 2.1.4 (and then upgrade our minimum dep in pyOpenSSL to 2.1.4, d’oh)