---
cve: "CVE-2026-39831"
severity: "CRITICAL"
cvss: 9.1
epss: "42%"
vendor: "golang.org/x/crypto"
kev: false
exploited: false
published: "2026-05-22 04:16:22"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-08T01:16:38+02:00"
---

# CVE-2026-39831

> 9.1 CRITICAL

## Beschreibung

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.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Keine | good |

## Patch verfügbar (OSV)

- a1c0d9929856c8aba2b31f079340f00578eda803 (Commit)

## Referenzen

- <https://go.dev/issue/79566>
- <https://groups.google.com/g/golang-announce/c/a082jnz-LvI>
- <https://go.dev/cl/781662>
- <https://pkg.go.dev/vuln/GO-2026-5019>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-39831) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_