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CVE-2026-39831: crypto vulnerability
CVE-2026-39831: critical vulnerability affecting crypto. Check CVSS, KEV status, business impact and recommended administrator actions.
- CVSS
- 9.1 CRITICAL
- EPSS
- 34.45%
- Known exploited
- not in KEV
- Product
- crypto
What is known
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.
Business impact
Successful exploitation of CVE-2026-39831, a critical vulnerability (CVSS 9.1) affecting crypto, may affect the confidentiality, integrity or availability of the vulnerable environment. The exact impact depends on the installed version, exposed interfaces and deployment configuration.
Recommended administrator action
Confirm whether crypto is present and compare installed versions with the vendor advisory and NVD record. Apply the vendor patch or documented mitigation; until remediation is complete, reduce exposure of affected interfaces, review relevant logs and monitor for indicators of exploitation. DataHouse can support version verification, managed patching, network exposure reduction, log review and backup validation for dedicated, cloud and colocated environments.