Certificate trust bypass via wildcard constraint mismatch
Published Aug 3, 2026 · Updated Aug 3, 2026
Improper certificate validation in cryptography before 49.0.0 allows remote attackers to make invalid certificate chains pass verification. DNSConstraint::matches treated a wildcard DNS SAN as matching a narrower permittedSubtrees constraint, although the wildcard also covers sibling names outside that subtree. Exploitation requires a constrained intermediate CA and an overbroad wildcard leaf SAN; accepted chains gain trust for names the CA was not permitted to certify.
Summary
What happened
Improper certificate validation in cryptography before 49.0.0 allows remote attackers to make invalid certificate chains pass verification. DNSConstraint::matches treated a wildcard DNS SAN as matching a narrower permittedSubtrees constraint, although the wildcard also covers sibling names outside that subtree. Exploitation requires a constrained intermediate CA and an overbroad wildcard leaf SAN; accepted chains gain trust for names the CA was not permitted to certify.
The record
- CVE
- CVE-2026-69248
- Published
- Aug 3, 2026
- Updated
- Aug 3, 2026
- Vendor
- Python Cryptographic Authority
- Product
- cryptography
- Classifications
- CWE-295, T1553
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 3, 2026CVE publishedPublication date reported by the CVE source.
- Aug 3, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 49.0.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Standalone wildcard permittedSubtrees escape PoCproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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