{"cve":"CVE-2026-39831","nvd":{"published":"2026-05-22T04:16:22.553","modified":"2026-07-23T16:10:00.137","status":"Analyzed","description":"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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","score":9.1},"cwes":["CWE-862"],"references":["https://go.dev/cl/781662","https://go.dev/issue/79566","https://groups.google.com/g/golang-announce/c/a082jnz-LvI","https://pkg.go.dev/vuln/GO-2026-5019"],"products":["golang:crypto"],"source":"nvd","synced_at":"2026-10-19T22:36:28.938604137+00:00"},"epss":{"cve":"CVE-2026-39831","score":0.00478,"percentile":0.41307,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-89gr-r52h-f8rx","url":"https://osv.dev/vulnerability/GHSA-89gr-r52h-f8rx","summary":"golang.org/x/crypto: FIDO/U2F security key physical presence check can be bypassed","modified":"2026-09-10T03:50:48.773810556Z","packages":[{"ecosystem":"Go","name":"golang.org/x/crypto","purl":"pkg:golang/golang.org/x/crypto","ranges":["<0.52.0"],"fixed":["0.52.0"]}]},{"id":"GO-2026-5019","url":"https://osv.dev/vulnerability/GO-2026-5019","summary":"Invoking bypass of FIDO/U2F security keys physical interaction in golang.org/x/crypto/ssh","modified":"2026-09-17T10:41:36.871169141Z","packages":[{"ecosystem":"Go","name":"golang.org/x/crypto","purl":"pkg:golang/golang.org/x/crypto","ranges":["<0.52.0"],"fixed":["0.52.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}