CVE-2026-56854

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

Published: Aug 28, 2026Updated: Sep 3, 2026 Sources: CVE List NVDCWE-863

7.5HIGH

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.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:NPrivileges Required

None

UI:NUser Interaction

None

Scope

S:UScope

Unchanged

Impact

C:HConfidentiality

High

I:NIntegrity

None

A:NAvailability

None

Open in CVSS calculator →

Weaknesses

CWE-863

Affected Products

golang.org/x/crypto

oss-projectaka x/crypto, golang x crypto

golang.org/x/crypto/sshLibrary

OSS Libraries / go

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

Is your org exposed to CVE-2026-56854?Request an assessment to establish which checks are appropriate for your systems. Check my exposure

Attack Graph

Products CVE Techniques Tactics

Click technique nodes for MITRE ATT&CK details · drag to pan · Ctrl/⌘ + scroll to zoom, or go fullscreen.

MITRE ATT&CK

2 techniques

Initial Access

View detailed technique mapping

References

https://go.dev/issue/80213

go.dev

https://go.dev/cl/797040

go.dev

https://pkg.go.dev/vuln/GO-2026-6303

pkg.go.dev

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2026-56854 and every CVE in our database. Create a free account — no credit card required.

Create Free Account

Plain-language analysis

Impact assessment and exploitation scenario in plain English

Attack graph visualization

Interactive attack path and kill chain mapping

Exploit details & PoC links

ExploitDB, Metasploit, GitHub PoCs with direct links

Nuclei scanner templates

Ready-to-use vulnerability scanner templates

Full remediation guide

Patch instructions, workarounds, and compliance impact

Interactive AI chat

Ask questions about this vulnerability in natural language

Related vulnerabilities

Semantically similar CVEs and attack patterns

REST API & MCP access

Integrate vulnerability data into your workflows