Is CVE-2026-56854 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-56854 being exploited in the wild.

How severe is CVE-2026-56854?

High severity, with a CVSS score of 7.5, published 28 August 2026.

Which products and versions are affected?

golang.org/x/crypto (Go) SEMVER:introduced=0,fixed=0.55.0; golang.org/x/crypto/ssh (Go) prior to fix.

Is there a fix for CVE-2026-56854?

Yes. golang.org/x/crypto (Go): upgrade to 0.55.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-56854 attacked?

It is attacked over the network.

Am I affected by CVE-2026-56854?

Check whether you run golang.org/x/crypto (Go) or golang.org/x/crypto/ssh (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-56854: Go SSH source-address permission validation bypass in authentication callbacks

CVE-2026-56854 · Severity: high · CVSS 7.5 · Published 2026-08-28

An SSH authentication library in Go failed to properly validate source-address restrictions for most authentication methods. Attackers could bypass IP-based access controls set through password, keyboard-interactive, or other authentication callbacks, allowing unauthorized access from restricted IP ranges. This represents a partial failure of an intended security control, leaving organizations vulnerable even when they believed IP-based restrictions were in place.

Technologies: golang.org/x/crypto (Go), golang.org/x/crypto/ssh (Go). Vendors: Go.

Quick answers

Is CVE-2026-56854 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-56854 being exploited in the wild.
How severe is CVE-2026-56854?: High severity, with a CVSS score of 7.5, published 28 August 2026.
Which products and versions are affected?: golang.org/x/crypto (Go) SEMVER:introduced=0,fixed=0.55.0; golang.org/x/crypto/ssh (Go) prior to fix.
Is there a fix for CVE-2026-56854?: Yes. golang.org/x/crypto (Go): upgrade to 0.55.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-56854 attacked?: It is attacked over the network.
Am I affected by CVE-2026-56854?: Check whether you run golang.org/x/crypto (Go) or golang.org/x/crypto/ssh (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

golang.org/x/crypto (Go): upgrade to 0.55.0 or later
```
go get golang.org/x/crypto@v0.55.0
```

Technical details

The vulnerability is a permission validation bypass in Go's SSH implementation where source-address restrictions were only enforced for PublicKeyCallback and VerifiedPublicKeyCallback authentication methods. PasswordCallback, KeyboardInteractiveCallback, NoClientAuthCallback, and GSSAPIWithMICConfig.AllowLogin callbacks silently ignored source-address restrictions in their returned Permissions objects. An attacker with valid credentials could connect from IP addresses that should have been blocked by source-address restrictions, making the control ineffective for these authentication paths. The fix applies source-address validation uniformly across all authentication callback types.

Affected products

Go golang.org/x/crypto/ssh prior to fix

Identifiers

CVE-2026-56854
GO-2026-6303

Timeline

2026-08-28: disclosed
2026: patched: Fix available in Go CL/797040

References

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