{"schema":"threatline.record/2","record":{"id":"CVE-2026-109399","aliases":[],"summary":"SWUpdate through 2026.05.1 CMS Signature Verification Bypass via Embedded Intermediates","details":"SWUpdate through 2026.05.1 contains an improper certificate validation vulnerability in crypto/swupdate_cms_verify_openssl.c that trusts untrusted X.509 certificates embedded in CMS SignedData for chain building. Attackers holding a signing key from a sibling intermediate under the same root can embed that intermediate in the signature to install malicious updates.","categories":["Unclassified"],"product":"swupdate","vendor":"sbabic","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-109399","source_modified_at":"2026-10-18T12:03:15.694Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"swupdate","vendor":"sbabic","versions":[{"version":"0","lessThanOrEqual":"2026.05.1","status":"affected","versionType":"custom"}],"defaultStatus":"unaffected"}],"fixed_versions":[],"cvss":9.2,"severity":"Critical","kev":{"listed":false},"epss":{"probability":0.0021,"percentile":0.10635,"score_date":"2026-10-23"},"published_at":"2026-10-12T15:16:44.440Z","modified_at":"2026-10-18T12:03:15.694Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-109399","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-18T12:03:15.694Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-109399","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://groups.google.com/g/swupdate/c/dsoMcGFnEns","tags":["technical-description","mailing-list"]},{"source":"CVE List","url":"https://github.com/sbabic/swupdate/commit/e66c5640664a31668926a24c0c84b6b6570dc0d9","tags":["patch"]},{"source":"CVE List","url":"https://github.com/sbabic/swupdate/blob/2026.05.1/crypto/swupdate_cms_verify_openssl.c","tags":["technical-description"]},{"source":"CVE List","url":"https://github.com/sbabic/swupdate","tags":["product"]},{"source":"CVE List","url":"https://www.vulncheck.com/advisories/swupdate-through-2026.05.1-cms-signature-verification-bypass-via-embedded-intermediates","tags":["third-party-advisory"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"none","automatable":"no","technical_impact":"total","assessed_at":"2026-10-18T11:47:38.050733Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":null,"confidence":"unknown","reviewed":false},"change_timestamp":"2026-10-18T12:03:15.694Z","content_hash":"62ea372ebc8633439995456e9d0a33f212b27cd959d800d2db929a8f322f0c55"}}