High severity · published Aug 28, 2026
CVE-2026-56854
Source-address critical option not enforced for non-public-key auth callbacks in golang.org/x/crypto/ssh
7.5
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 38% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
GO
golang.org/x/crypto/ssh · golang.org/x/crypto
before 0.55.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-56854
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-56854
go.dev
https://go.dev/cl/797040
go.dev
https://go.dev/issue/80213
pkg.go.dev
https://pkg.go.dev/vuln/GO-2026-6303
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