CVE-2026-97031

Reject malformed ECH outer extension references in crypto/tls

Published Oct 8, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
Multiple ECH outer extension references are not permitted under RFC 9849; previously, a client could send a well-crafted packet that could trigger memory exhaustion in the server process by specifying multiple references. We now reject these as malformed and curb the memory amplification vector as a result.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

No advisories available
History
Type Values Removed Values Added
Weaknesses CWE-405
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-400
Type Values Removed Values Added
First Time appeared Go Standard Library
Go Standard Library crypto Tls
Vendors & Products Go Standard Library
Go Standard Library crypto Tls
Type Values Removed Values Added
Weaknesses CWE-400
Type Values Removed Values Added
Weaknesses CWE-770
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Important

Type Values Removed Values Added
Description Multiple ECH outer extension references are not permitted under RFC 9849; previously, a client could send a well-crafted packet that could trigger memory exhaustion in the server process by specifying multiple references. We now reject these as malformed and curb the memory amplification vector as a result.
Title Reject malformed ECH outer extension references in crypto/tls
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Go
Published
Updated
Oct 9, 2026, 3:59 PM
Reserved
Sep 23, 2026, 11:03 PM
Status
Awaiting Analysis
Published
Oct 8, 2026, 11:17 PM
Modified
Oct 9, 2026, 4:35 PM
Severity
Important
Public date
Oct 8, 2026, 10:53 PM