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Critical, CVSS 9.1

golang.org/x/crypto: FIDO/U2F security key physical presence check can be bypassed

CVE-2026-39831GHSA-89gr-r52h-f8rx

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (golang.org/x/crypto 0.52.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
9.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS
  • CVE-2026-39831: 0.48% estimated exploitation activity in the next 30 days; percentile 41.35 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

The Verify() method for FIDO/U2F security key types (sk-ecdsa-sha2-nistp256@openssh.com, sk-ssh-ed25519@openssh.com) did not check the User Presence flag. Signatures generated without physical touch were accepted, allowing unattended use of a hardware security key. To restore the previous behavior, return a "no-touch-required" extension in Permissions.Extensions from PublicKeyCallback.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-89gr-r52h-f8rx

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-39831

Advisory: golang.org/x/crypto: FIDO/U2F security key physical presence check can be bypassed
IDs: CVE-2026-39831, GHSA-89gr-r52h-f8rx
Record: https://patchnext.com/advisories/cve-2026-39831 (revision 1, source checked 26 Oct 2026, 15:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: golang.org/x/crypto 0.52.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go golang.org/x/crypto: affected < 0.52.0; fixed in 0.52.0

## Suggested inspection (read-only)
- Go golang.org/x/crypto: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on golang.org/x/crypto.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-89gr-r52h-f8rx (GitHub-reviewed advisory GHSA-89gr-r52h-f8rx lists affected ranges: Go golang.org/x/crypto >=0 <0.52.0)

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