VU#948176: Multiple TLS Libraries can Bypass Delegation Enforcement
CERT/CC says TLS libraries inconsistently enforce Name Constraints, with three assigned CVEs already fixed.
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Vulnerability3 · 1 read
CVE-2026-34073
- CVSS 4.0
- 1.7 low
- EPSS
- <1%p5
- Published
- ·
- Modified
Description · NVD
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.
- Vendors
- cryptography.io
- Products
- cryptography
- Weakness
- CWE-295
- 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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
In the news
3 storiesMultiple TLS libraries: X.509 Name Constraints enforcement bypasses (CVE-2026-34073, CVE-2026-3833, CVE-2026-5263, CVE-2026-33810; CERT/CC VU#573195, VU#948176, VU#410595)
Multiple TLS libraries bypass X.509 name-constraint checks, tracked in four CVEs and three CERT/CC notes.
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VU#573195: Go, OpenSSL, Apple, LibreSSL, pyca, wolfSSL Name-Constraint Inconsistency in RFC 5280 Implementation
CERT/CC warns TLS libraries inconsistently enforce X.509 name constraints, with fixes for GnuTLS and pyca/cryptography.
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