What happened
cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. In versions 45.0.0 through 48.0.0, if an intermediate constrained CA permits the DNS name foo.example.com, and the leaf certificate has a wildcard in its DNS SAN of *.example.com, python-cryptography's verifier accepts which allows escaping outside of the permitted names. The core issue is in DNSConstraint::matches, where a wildcard pattern was treated as matching a more-specific permitted constraint even though *.example.com can expand to sibling names such as bar.example.com outside foo.example.com. This allows acceptance of an invalid certificate chain. This issue is fixed in 49.0.0.
Affected versions
cryptography: < 49.0.0 Fixed: See vendor advisory.
Why it matters
Review the vendor advisory and exposure of the affected product to determine operational impact.
Detection & mitigation
- Apply vendor-provided updates or mitigations.
- Review affected product exposure and access logs.
Public PoC references
No public PoC reference has passed the current publication threshold.