Vulnerability in Cryptography.io Cryptography
CVE-2026-34073
cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. Prior to version 46.0.6, DNS name constraints were only validated against SANs within child certificates, and not the "peer name" presented during each validation. Consequently, cryptography would allow a peer named bar.example.com to validate against a wildcard leaf certificate for *.example.com, even if the leaf's parent certificate (or upwards) contained an excluded subtree constraint for bar.example.com. This issue has been patched in version 46.0.6.
Vulnerability class: Improper Certificate Validation
EPSS: 0.002 (4.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
Affected products
- Cryptography.io Cryptography
- Pyca Cryptography — versions < 46.0.6
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-34073?
- CVE-2026-34073 is a medium-severity vulnerability in Cryptography.io Cryptography, classified under Improper Certificate Validation. CVSS score: 5.3/10. Published 2026-03-31.
- How severe is CVE-2026-34073?
- Medium severity. CVSS v3 base score is 5.3 out of 10.