State-Advancing Vulnerability in Go Language Server Product
CVE-2026-56862

7.5HIGH

Key Information:

Vendor

Go Standard Library

Status
Crypto/tls
Vendor
CVE Published:
13 August 2026

What is CVE-2026-56862?

This vulnerability in the Go programming language allows a malicious client to exploit the KeyUpdate handshake messages. The issue arises because the server treats these messages as state-advancing, which means it continues key derivation operations indefinitely, even before the handshake process is completed. This can potentially create a denial of service, as the server resources are continuously engaged in unnecessary processing. Developers using the affected versions should patch this vulnerability to ensure their applications are secure.

Affected Version(s)

crypto/tls 0 < 1.25.13

crypto/tls 1.26.0-0 < 1.26.6

crypto/tls 1.27.0-0 < 1.27.0-rc.3

References

https://go.dev/issue/80528
https://go.dev/cl/804261
https://groups.google.com/g/golang-announce/c/94pEornpRlI

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Qi Deng of Aurascape.ai
.