Improper Certificate Validation in python-cryptography - CVE-2026-34073
Published: April 8, 2026
Vulnerability identifier: #VU125338
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-34073
CWE-ID: CWE-295
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Python Cryptographic Authority
Affected software:
python-cryptography
python-cryptography
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass certificate name constraints validation.
The vulnerability exists due to improper certificate validation in the X.509 certificate validation logic when validating a peer name against a wildcard SAN certificate chain. A remote attacker can present a crafted certificate chain to bypass certificate name constraints validation.
Exploitation requires an uncommon X.509 topology involving an excluded subtree constraint that matches the peer name.
How to mitigate CVE-2026-34073
Install security update from vendor's website.