Go ssh up to 0.54.x Authentication Callback authorization

Summaryinfo

A vulnerability, which was classified as critical, was found in Go ssh up to 0.54.x. This affects an unknown function of the component Authentication Callback. Such manipulation leads to authorization. This vulnerability is traded as CVE-2026-56854. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in Go ssh up to 0.54.x and classified as critical. Affected by this issue is some unknown functionality of the component Authentication Callback. The manipulation with an unknown input leads to a authorization vulnerability. Using CWE to declare the problem leads to CWE-863. The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at go.dev. This vulnerability is handled as CVE-2026-56854 since 06/23/2026. The exploitation is known to be easy. The attack may be launched remotely. The technical details are unknown and an exploit is not available.

Upgrading to version 0.55.0 eliminates this vulnerability.

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Productinfo

Type

• SSH Server Software

Vendor

• Go

Name

• ssh

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21
• 0.22
• 0.23
• 0.24
• 0.25
• 0.26
• 0.27
• 0.28
• 0.29
• 0.30
• 0.31
• 0.32
• 0.33
• 0.34
• 0.35
• 0.36
• 0.37
• 0.38
• 0.39
• 0.40
• 0.41
• 0.42
• 0.43
• 0.44
• 0.45
• 0.46
• 0.47
• 0.48
• 0.49
• 0.50
• 0.51
• 0.52
• 0.53
• 0.54

License

• open-source

CPE 2.3info

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CPE 2.2info

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