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CVE-2026-9648

34
FAUCET Score

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.

First published: Jun 11, 2026Last modified: Jun 11, 2026

Impacted Technologies

VendorProductVersion(s)CPE
Haskell Programming LanguageCrypton-Certificate
>= 0, < 1.9.1CNA affected

CVSS Data

CVSS version used by this source: 3.1

9.1CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.22%
Probability of exploitation in next 30 days
EPSS Percentile
13.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0022 is in the 1st percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

kb.cert.org / vuls/id/862559
github.com / haskell/security-advisories/pull/332
github.com / kazu-yamamoto/crypton-certificate/pull/30
github.com / kazu-yamamoto/crypton-certificate/pull/30/changes/f4b77edf6ead77f4a886da40e41eab20f0180e39
hackage.haskell.org / package/crypton-x509-validation-1.9.1/revisions