CVE-2026-56854

Source-address critical option not enforced for non-public-key auth callbacks in golang.org/x/crypto/ssh

Published Aug 28, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
The source-address critical option in the Permissions returned by an authentication callback was only enforced for the PublicKeyCallback and VerifiedPublicKeyCallback paths, extending the fix for CVE-2026-46595. Permissions returned by the PasswordCallback, KeyboardInteractiveCallback, NoClientAuthCallback, and GSSAPIWithMICConfig.AllowLogin callbacks were not validated against the client's remote address, so a source-address restriction set by those callbacks was silently ignored. The check is now applied to the Permissions returned by any authentication callback.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

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History
Type Values Removed Values Added
Weaknesses CWE-285
Type Values Removed Values Added
Weaknesses CWE-863
Metrics cvssV3_1

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

ssvc

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

Type Values Removed Values Added
First Time appeared Golang
Golang crypto
Vendors & Products Golang
Golang crypto
Type Values Removed Values Added
Weaknesses CWE-285
Type Values Removed Values Added
Description The source-address critical option in the Permissions returned by an authentication callback was only enforced for the PublicKeyCallback and VerifiedPublicKeyCallback paths, extending the fix for CVE-2026-46595. Permissions returned by the PasswordCallback, KeyboardInteractiveCallback, NoClientAuthCallback, and GSSAPIWithMICConfig.AllowLogin callbacks were not validated against the client's remote address, so a source-address restriction set by those callbacks was silently ignored. The check is now applied to the Permissions returned by any authentication callback.
Title Source-address critical option not enforced for non-public-key auth callbacks in golang.org/x/crypto/ssh
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Go
Published
Updated
Aug 28, 2026, 8:17 PM
Reserved
Jun 23, 2026, 3:10 PM
Status
Awaiting Analysis
Published
Aug 28, 2026, 4:18 PM
Modified
Sep 3, 2026, 4:37 PM
Severity
Critical
Public date
Aug 28, 2026, 3:14 PM