CVE-2026-56855

Prevent DoS on deadlocked established channel in golang.org/x/crypto/ssh

Published Sep 2, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
CPEs cpe:2.3:a:golang:crypto:*:*:*:*:*:go:*:*
Type Values Removed Values Added
Weaknesses CWE-667
Type Values Removed Values Added
First Time appeared Golang
Golang crypto
Vendors & Products Golang
Golang crypto
Type Values Removed Values Added
Weaknesses CWE-770
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-667
Type Values Removed Values 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.
Title Prevent DoS on deadlocked established channel in golang.org/x/crypto/ssh
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Go
Published
Updated
Sep 3, 2026, 2:14 PM
Reserved
Jun 23, 2026, 3:10 PM
Status
Analyzed
Published
Sep 2, 2026, 8:17 PM
Modified
Sep 4, 2026, 4:34 PM
Severity
Moderate
Public date
Sep 2, 2026, 7:37 PM