CVE-2026-56855
SSH Protocol Implementation Denial of Service Vulnerability
Description
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.
INFO
Published Date :
Sept. 2, 2026, 8:17 p.m.
Last Modified :
Sept. 2, 2026, 8:17 p.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-56855
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Handle all RFC 4254 channel messages explicitly.
- Treat unknown messages as protocol errors.
- Tear down connections instead of buffering.
- Update the system to handle messages correctly.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-56855.
| URL | Resource |
|---|---|
| https://go.dev/cl/826524 | |
| https://go.dev/issue/81317 | |
| https://groups.google.com/g/golang-announce/c/1y3fb2np35U | |
| https://pkg.go.dev/vuln/GO-2026-6355 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-56855 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-56855
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-56855 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-56855 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Sep. 02, 2026
Action Type Old Value New Value Added Description 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. Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/56xxx/CVE-2026-56855.json">CVE-2026-56855</a> Added Reference https://go.dev/cl/826524 Added Reference https://go.dev/issue/81317 Added Reference https://groups.google.com/g/golang-announce/c/1y3fb2np35U Added Reference https://pkg.go.dev/vuln/GO-2026-6355