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PatchSiren cyber security CVE debrief

CVE-2026-9648 Haskell Programming Language CVE debrief

The crypton-x509-validation Haskell library fails to enforce X.509 NameConstraints, allowing TLS clients to accept certificates whose Subject Alternative Names fall outside the issuing CA’s permitted subtrees. This oversight enables an attacker who compromises a name-constrained sub-CA to impersonate domains beyond its intended scope.

Vendor
Haskell Programming Language
Product
crypton-certificate
CVSS
CRITICAL 9.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-11
Original CVE updated
2026-06-11
Advisory published
2026-06-11
Advisory updated
2026-06-11

Who should care

Users of the crypton-x509-validation Haskell library, particularly those involved in certificate validation and TLS communications.

Technical summary

The library's failure to enforce X.509 NameConstraints allows for potential impersonation attacks by compromising a name-constrained sub-CA.

Defensive priority

High

Recommended defensive actions

  • Update to the latest version of the crypton-x509-validation library.
  • Review and update certificate validation processes to ensure proper enforcement of X.509 NameConstraints.

Evidence notes

The CVE-2026-9648 record indicates a critical vulnerability in the crypton-x509-validation library with a CVSS score of 9.1.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-9648 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-9648

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-9648 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-9648

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.