CVE-2026-34073

cryptography has incomplete DNS name constraint enforcement on peer names

Published Mar 31, 2026 CVSS 4.0 · 1.7 Low EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-m959-cc7f-wv43 cryptography has incomplete DNS name constraint enforcement on peer names
History
Type Values Removed Values Added
First Time appeared Cryptography.io
Cryptography.io cryptography
CPEs cpe:2.3:a:cryptography.io:cryptography:*:*:*:*:*:python:*:*
Vendors & Products Cryptography.io
Cryptography.io cryptography
Metrics cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N'}

cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'}

Type Values Removed Values Added
First Time appeared Pyca
Pyca cryptography
Vendors & Products Pyca
Pyca cryptography
References
Metrics threat_severity

None

cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N'}

threat_severity

Low

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title cryptography has incomplete DNS name constraint enforcement on peer names
Weaknesses CWE-295
References
Metrics cvssV4_0

{'score': 1.7, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Oct 14, 2026, 4:07 PM
Reserved
Mar 25, 2026, 4:21 PM
Status
Modified
Published
Mar 31, 2026, 3:15 AM
Modified
Oct 14, 2026, 5:18 PM
Severity
Low
Public date
Mar 31, 2026, 2:04 AM