CVE-2026-88647

gnutls: gnutls: Information disclosure via hostname verification bypass

Published Oct 8, 2026 CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed
Description
GnuTLS v3.8.13 can perhaps unexpectedly trust a certificate on the basis of Common Name when Subject Alternative Name has an SRV otherName (1.3.6.1.5.5.7.8.7) whose value is an OCTET STRING. NOTE: the Supplier does not consider this an actionable security vulnerability because of its "threat model doesn't consider attacks only possible by modifying anything within the trust boundary (private keys, trusted certificate authorities and their issued certificates including intermediate CAs, etc.)" policy.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Description A hostname verification bypass in GnuTLS v3.8.13 allows attackers to circumvent the Common Name fallback mechanism and eavesdrop on communications via a crafted certificate. GnuTLS v3.8.13 can perhaps unexpectedly trust a certificate on the basis of Common Name when Subject Alternative Name has an SRV otherName (1.3.6.1.5.5.7.8.7) whose value is an OCTET STRING. NOTE: the Supplier does not consider this an actionable security vulnerability because of its "threat model doesn't consider attacks only possible by modifying anything within the trust boundary (private keys, trusted certificate authorities and their issued certificates including intermediate CAs, etc.)" policy.
References
Type Values Removed Values Added
References
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
References
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-297
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'}

Type Values Removed Values Added
First Time appeared Gnu
Gnu gnutls
Vendors & Products Gnu
Gnu gnutls
Type Values Removed Values Added
Weaknesses CWE-640
Type Values Removed Values Added
Title GnuTLS 3.8.13 Hostname Verification Bypass Enables Eavesdropping gnutls: gnutls: Information disclosure via hostname verification bypass
Weaknesses CWE-295
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}

threat_severity

Important

Type Values Removed Values Added
Title GnuTLS 3.8.13 Hostname Verification Bypass Enables Eavesdropping
Weaknesses CWE-640
Type Values Removed Values Added
Description A hostname verification bypass in GnuTLS v3.8.13 allows attackers to circumvent the Common Name fallback mechanism and eavesdrop on communications via a crafted certificate.
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
mitre
Published
Updated
Nov 4, 2026, 4:52 AM
Reserved
Sep 10, 2026, 12:00 AM
Status
Awaiting Analysis
Published
Oct 8, 2026, 5:17 PM
Modified
Nov 4, 2026, 5:19 AM
Severity
Important
Public date
Oct 8, 2026, 12:00 AM