CVE intelligence

CVE-2026-56855

Vulnerability intelligence

Published Sep 2, 2026Sources checked Oct 27, 2026

7.5HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-56855 and is rated High severity with a CVSS score of 7.5. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Oct 22, 2026

Vendor remediation details

Release Notes

Vendor-listed releases

8.7.11-9
0.14.0-17
2.27.0-14
1.30.10-30
1.8.4-2
1.12.15-14
2.101.0-1
25.0.3-21
1.9.5-21
1.31.0-33

CISA KEVNot listedBased on the latest collected catalog

EPSS0.5%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-56855?

Previously, after a channel has been established, a malicious peer could send crafted messages that would deadlock the entire connection. Now, we handle all RFC 4254 channel messages; global requests are handled explicitly.

Then, treat all other messages as a protocol error and tear the connection down instead of buffering and blocking.

Source: NVD