TLS domain impersonation via unenforced NameConstraints
Published Jun 11, 2026 · Updated Jun 11, 2026
Improper certificate validation in crypton-x509-validation 1.6.12 through 1.9.0 allows remote attackers to impersonate TLS domains. The certificate-chain validation path does not apply issuing CAs' permitted and excluded NameConstraints subtrees to leaf Subject Alternative Names, so out-of-scope names pass validation. Exploitation requires control of a name-constrained sub-CA private key and enables man-in-the-middle reading or modification of TLS traffic.
Summary
What happened
Improper certificate validation in crypton-x509-validation 1.6.12 through 1.9.0 allows remote attackers to impersonate TLS domains. The certificate-chain validation path does not apply issuing CAs' permitted and excluded NameConstraints subtrees to leaf Subject Alternative Names, so out-of-scope names pass validation. Exploitation requires control of a name-constrained sub-CA private key and enables man-in-the-middle reading or modification of TLS traffic.
The record
- CVE
- CVE-2026-9648
- Published
- Jun 11, 2026
- Updated
- Jun 11, 2026
- Vendor
- Kazu Yamamoto
- Product
- crypton-x509-validation
- Classifications
- CWE-295, T1557
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 11, 2026CVE publishedPublication date reported by the CVE source.
- Jun 11, 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?
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- Affected versionversion=0 <1.9.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
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Your stack
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