{"id":"UBUNTU-CVE-2026-109399","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.","modified":"2026-10-17T12:59:49.369275356Z","published":"2026-10-12T16:17:00Z","upstream":["CVE-2026-109399"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-109399"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-109399"},{"type":"REPORT","url":"https://github.com/sbabic/swupdate"},{"type":"REPORT","url":"https://github.com/sbabic/swupdate/blob/2026.05.1/crypto/swupdate_cms_verify_openssl.c"},{"type":"REPORT","url":"https://github.com/sbabic/swupdate/commit/e66c5640664a31668926a24c0c84b6b6570dc0d9"},{"type":"REPORT","url":"https://groups.google.com/g/swupdate/c/dsoMcGFnEns"},{"type":"REPORT","url":"https://www.vulncheck.com/advisories/swupdate-through-2026.05.1-cms-signature-verification-bypass-via-embedded-intermediates"}],"affected":[{"package":{"name":"swupdate","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/swupdate?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2020.11-2","2021.04-1.1","2021.04-2","2021.04-2build1","2021.11-1"],"ecosystem_specific":{"binaries":[{"binary_name":"libswupdate0.1","binary_version":"2021.11-1"},{"binary_name":"lua-swupdate","binary_version":"2021.11-1"},{"binary_name":"swupdate","binary_version":"2021.11-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-109399.json"}},{"package":{"name":"swupdate","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/swupdate?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2023.05+dfsg-3","2023.05+dfsg-4","2023.05+dfsg-4build1","2023.05+dfsg-5","2023.12+dfsg-1","2023.12.1+dfsg-1ubuntu1","2023.12.1+dfsg-1ubuntu4","2023.12.1+dfsg-1ubuntu5"],"ecosystem_specific":{"binaries":[{"binary_name":"libswupdate0.1","binary_version":"2023.12.1+dfsg-1ubuntu5"},{"binary_name":"lua-swupdate","binary_version":"2023.12.1+dfsg-1ubuntu5"},{"binary_name":"swupdate","binary_version":"2023.12.1+dfsg-1ubuntu5"},{"binary_name":"swupdate-www","binary_version":"2023.12.1+dfsg-1ubuntu5"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-109399.json"}},{"package":{"name":"swupdate","ecosystem":"Ubuntu:26.10","purl":"pkg:deb/ubuntu/swupdate?arch=source&distro=stonking"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2025.12+dfsg-4ubuntu1","2026.05+dfsg-3ubuntu2","2026.05+dfsg-4ubuntu1","2026.05.1+dfsg-1ubuntu1","2026.05.1+git20261001+dfsg-1ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_name":"libswupdate0.1","binary_version":"2026.05.1+git20261001+dfsg-1ubuntu1"},{"binary_name":"lua-swupdate","binary_version":"2026.05.1+git20261001+dfsg-1ubuntu1"},{"binary_version":"2026.05.1+git20261001+dfsg-1ubuntu1","binary_name":"swupdate"},{"binary_version":"2026.05.1+git20261001+dfsg-1ubuntu1","binary_name":"swupdate-www"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-109399.json"}},{"package":{"name":"swupdate","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/swupdate?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2025.05+dfsg-2ubuntu1","2025.05+dfsg-3ubuntu1","2025.12+dfsg-1ubuntu1","2025.12+dfsg-2ubuntu1","2025.12+dfsg-3ubuntu1","2025.12+dfsg-4ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_name":"libswupdate0.1","binary_version":"2025.12+dfsg-4ubuntu1"},{"binary_name":"lua-swupdate","binary_version":"2025.12+dfsg-4ubuntu1"},{"binary_name":"swupdate","binary_version":"2025.12+dfsg-4ubuntu1"},{"binary_name":"swupdate-www","binary_version":"2025.12+dfsg-4ubuntu1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-109399.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}