{"id":"UBUNTU-CVE-2026-42784","details":"A flaw was found in sequoia-openpgp. The library incorrectly infers key flags for older certificates when a key flags subpacket is missing, leading to a discrepancy in how key capabilities are viewed. This key flag confusion allows an attacker to bypass the back-signature check. Consequently, an attacker can illegitimately bind an arbitrary subkey to their own certificate and forge signatures, completely compromising cryptographic integrity.","modified":"2026-09-24T02:00:15.797648506Z","published":"2026-09-16T17:17:00Z","upstream":["CVE-2026-42784"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-42784"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-42784"}],"affected":[{"package":{"name":"rust-sequoia-openpgp","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/rust-sequoia-openpgp?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1.0-3","1.3.0-4","1.7.0-6"],"ecosystem_specific":{"binaries":[{"binary_name":"librust-sequoia-openpgp+bzip2-dev","binary_version":"1.7.0-6"},{"binary_name":"librust-sequoia-openpgp+compression-bzip2-dev","binary_version":"1.7.0-6"},{"binary_name":"librust-sequoia-openpgp+compression-deflate-dev","binary_version":"1.7.0-6"},{"binary_version":"1.7.0-6","binary_name":"librust-sequoia-openpgp+compression-dev"},{"binary_name":"librust-sequoia-openpgp+default-dev","binary_version":"1.7.0-6"},{"binary_name":"librust-sequoia-openpgp+flate2-dev","binary_version":"1.7.0-6"},{"binary_name":"librust-sequoia-openpgp+nettle-dev","binary_version":"1.7.0-6"},{"binary_name":"librust-sequoia-openpgp-dev","binary_version":"1.7.0-6"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42784.json"}},{"package":{"name":"rust-sequoia-openpgp","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/rust-sequoia-openpgp?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.16.0-1","1.17.0-1","1.17.0-2","1.18.0-1","1.19.0-1","1.19.0-1build1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.19.0-1build1","binary_name":"librust-sequoia-openpgp-dev"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42784.json"}},{"package":{"name":"rust-sequoia-openpgp","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/rust-sequoia-openpgp?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.22.0-1","2.0.0-2"],"ecosystem_specific":{"binaries":[{"binary_name":"librust-sequoia-openpgp-dev","binary_version":"2.0.0-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42784.json"}},{"package":{"name":"rust-sequoia-openpgp","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/rust-sequoia-openpgp?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.0-2","2.0.0-5","2.1.0-1","2.1.0-2","2.1.0-3","2.2.0-1"],"ecosystem_specific":{"binaries":[{"binary_name":"librust-sequoia-openpgp-dev","binary_version":"2.2.0-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-42784.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N"},{"type":"Ubuntu","score":"medium"}]}