CVE-2026-56862

Limit handshake messages we are willing to accept post-handshake in crypto/tls

Published: Aug 13, 2026Updated: Sep 3, 2026 Sources: CVE List NVDCWE-770

7.5HIGH

Description

Handshake messages, such as KeyUpdate, are always considered as state-advancing, regardless of whether a handshake has been completed or not. As a result, a malicious client can keep sending KeyUpdate messages to force the server to keep performing key derivation operations indefinitely.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:NPrivileges Required

None

UI:NUser Interaction

None

Scope

S:UScope

Unchanged

Impact

C:NConfidentiality

None

I:NIntegrity

None

A:HAvailability

High

Open in CVSS calculator →

Weaknesses

CWE-770

Affected Products

Go standard library

oss-project·USaka net/http, html/template, golang standard library, crypto/x509

crypto/tlsLibraryLibrary

OSS Libraries / go

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

Is your org exposed to CVE-2026-56862?Request an assessment to establish which checks are appropriate for your systems. Check my exposure

Attack Graph

Products CVE Techniques Tactics

Click technique nodes for MITRE ATT&CK details · drag to pan · Ctrl/⌘ + scroll to zoom, or go fullscreen.

MITRE ATT&CK

1 technique

Impact

View detailed technique mapping

References

https://go.dev/cl/804261

go.dev

https://go.dev/issue/80528

go.dev

https://groups.google.com/g/golang-announce/c/94pEornpRlI

groups.google.com

and 1 more references View all →

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2026-56862 and every CVE in our database. Create a free account — no credit card required.

Create Free Account

Plain-language analysis

Impact assessment and exploitation scenario in plain English

Attack graph visualization

Interactive attack path and kill chain mapping

Exploit details & PoC links

ExploitDB, Metasploit, GitHub PoCs with direct links

Nuclei scanner templates

Ready-to-use vulnerability scanner templates

Full remediation guide

Patch instructions, workarounds, and compliance impact

Interactive AI chat

Ask questions about this vulnerability in natural language

Related vulnerabilities

Semantically similar CVEs and attack patterns

REST API & MCP access

Integrate vulnerability data into your workflows