7.5High

CVE-2026-97031Reject malformed ECH outer extension references in crypto/tls

Go standard library crypto/tls Published: 2026-10-09 01:53 (1 month ago)

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.

Weakness (CWE): CWE-405

Data: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Published as the sources state it, in English.

Affected products and versions

Vendor	Product	Versions
Go standard library	crypto/tls	< 1.26.9, 1.27.0-0 – < 1.27.2

References and patches

CVSS score

7.5High

Source: CISA-ADP · CVSS 3.1

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

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

All scores (2)

CISA-ADP	CVSS 3.1	7.5High
134c704f-9b21-4f2e-91b3-4a467353bcc0	CVSS 3.1	7.5High

EPSS (chance of exploitation in 30 days)

0.72%

higher than 54% of all CVEs

CISA assessment (SSVC)

Exploitation: none
Automatable: yes
Technical impact: partial

Timeline

ID reserved2026-09-23
Published2026-10-09 01:53
Reached IP-DB2026-10-24 23:42
Last updated2026-10-09 19:35

Assigned by (CNA): Go
NVD status: Awaiting Analysis

View at source: CVE.org · NVD

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