Improper Certificate Validation Affecting cryptography package, versions [,46.0.6)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published29 Mar 2026
- disclosed27 Mar 2026
- credit1seal
Introduced: 27 Mar 2026
CVE-2026-34073 (opens in a new tab)How to fix?
Upgrade cryptography to version 46.0.6 or higher.
Overview
Affected versions of this package are vulnerable to Improper Certificate Validation through the NameChain DNS verification logic in src/rust/cryptography-x509-verification. An attacker can make a peer name, such as bar.example.com, validate against a wildcard leaf certificate like *.example.com even when an issuing certificate in the chain excludes that DNS subtree, causing improper certificate acceptance.
Notes
- The flaw affects X.509 path validation when DNS name constraints are present, and the leaf certificate uses a wildcard DNS SAN.
- The maintainers note that ordinary X.509 topologies, including those used by the Web PKI, are not affected, and exploitation requires an uncommon certificate hierarchy.