{"id":"CVE-2026-109399","title":"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","summary":"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 sign…","severity":"high","cvss":8.1,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-295"],"published":"2026-10-12","updated":"2026-10-12","sourceUpdated":"2026-10-12T16:17:05.557","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-109399","references":[{"url":"https://github.com/sbabic/swupdate","label":"disclosure@vulncheck.com"},{"url":"https://github.com/sbabic/swupdate/blob/2026.05.1/crypto/swupdate_cms_verify_openssl.c","label":"disclosure@vulncheck.com"},{"url":"https://github.com/sbabic/swupdate/commit/e66c5640664a31668926a24c0c84b6b6570dc0d9","label":"disclosure@vulncheck.com"},{"url":"https://groups.google.com/g/swupdate/c/dsoMcGFnEns","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/swupdate-through-2026.05.1-cms-signature-verification-bypass-via-embedded-intermediates","label":"disclosure@vulncheck.com"}],"tags":["nvd"],"ingestedAt":"2026-10-12T16:57:59.915Z","slug":"CVE-2026-109399","body":"## Overview\n\nSWUpdate 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":45,"depthScoreParts":{"impact":44.6,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}