CVE-2026-69248: CWE-295: Improper Certificate Validation in pyca cryptography
cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. In versions 45.0.0 through 48.0.0, if an intermediate constrained CA permits the DNS name foo.example.com, and the leaf certificate has a wildcard in its DNS SAN of *.example.com, python-cryptography's verifier accepts which allows escaping outside of the permitted names. The core issue is in DNSConstraint::matches, where a wildcard pattern was treated as matching a more-specific permitted constraint even though *.example.com can expand to sibling names such as bar.example.com outside foo.example.com. This allows acceptance of an invalid certificate chain. This issue is fixed in 49.0.0.
AI Analysis
Technical Summary
The pyca cryptography package before version 49.0.0 contains a certificate validation flaw (CWE-295) in the DNSConstraint::matches function. When an intermediate constrained CA permits a DNS name such as foo.example.com, and the leaf certificate contains a wildcard DNS SAN like *.example.com, the verifier incorrectly accepts the wildcard as matching the more specific permitted constraint. This allows certificates with DNS names outside the permitted scope (e.g., bar.example.com) to be accepted, effectively bypassing intended DNS name restrictions in certificate chains. The vulnerability is resolved in version 49.0.0.
Potential Impact
This vulnerability allows acceptance of invalid certificate chains that should be rejected due to DNS name constraints. This could undermine the trust model of TLS connections relying on pyca cryptography for certificate verification, potentially allowing attackers to impersonate domains outside the permitted DNS constraints. However, no known exploits in the wild have been reported.
Mitigation Recommendations
Upgrade pyca cryptography to version 49.0.0 or later, where this certificate validation issue is fixed. Patch status is confirmed by the vendor stating the fix is included in version 49.0.0. No other mitigations are indicated.
CVE-2026-69248: CWE-295: Improper Certificate Validation in pyca cryptography
Description
cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. In versions 45.0.0 through 48.0.0, if an intermediate constrained CA permits the DNS name foo.example.com, and the leaf certificate has a wildcard in its DNS SAN of *.example.com, python-cryptography's verifier accepts which allows escaping outside of the permitted names. The core issue is in DNSConstraint::matches, where a wildcard pattern was treated as matching a more-specific permitted constraint even though *.example.com can expand to sibling names such as bar.example.com outside foo.example.com. This allows acceptance of an invalid certificate chain. This issue is fixed in 49.0.0.
CVSS v4.0
Score 6.9medium
Affected software
pyca
cryptography
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The pyca cryptography package before version 49.0.0 contains a certificate validation flaw (CWE-295) in the DNSConstraint::matches function. When an intermediate constrained CA permits a DNS name such as foo.example.com, and the leaf certificate contains a wildcard DNS SAN like *.example.com, the verifier incorrectly accepts the wildcard as matching the more specific permitted constraint. This allows certificates with DNS names outside the permitted scope (e.g., bar.example.com) to be accepted, effectively bypassing intended DNS name restrictions in certificate chains. The vulnerability is resolved in version 49.0.0.
Potential Impact
This vulnerability allows acceptance of invalid certificate chains that should be rejected due to DNS name constraints. This could undermine the trust model of TLS connections relying on pyca cryptography for certificate verification, potentially allowing attackers to impersonate domains outside the permitted DNS constraints. However, no known exploits in the wild have been reported.
Mitigation Recommendations
Upgrade pyca cryptography to version 49.0.0 or later, where this certificate validation issue is fixed. Patch status is confirmed by the vendor stating the fix is included in version 49.0.0. No other mitigations are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-08-03T19:54:19.852Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a710cc4bf32cb7a34490878
Added to database: 08/03/2026, 21:48:52 UTC
Last enriched: 08/11/2026, 18:30:37 UTC
Last updated: 09/17/2026, 22:01:37 UTC
Views: 55
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