{"id":"USN-8431-1","summary":"ruby2.3, ruby2.5 vulnerabilities","details":"It was discovered that Ruby's Net::IMAP library did not properly verify\nthat Transport Layer Security (TLS) encryption was started after issuing a STARTTLS command. A remote\nattacker could possibly use this issue to perform a machine-in-the-middle attack and silently\nbypass TLS encryption. (CVE-2026-42246)\n\nIt was also discovered that Ruby's Net::IMAP library did not validate\nstring arguments passed to certain commands. A remote attacker could possibly use this issue to\ninject arbitrary IMAP commands. (CVE-2026-42257)","modified":"2026-06-16T01:04:08.521836337Z","published":"2026-06-15T17:24:17Z","related":["UBUNTU-CVE-2026-42246","UBUNTU-CVE-2026-42257"],"upstream":["CVE-2026-42246","CVE-2026-42257","UBUNTU-CVE-2026-42246","UBUNTU-CVE-2026-42257"],"references":[{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8431-1"},{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-42246"},{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-42257"}],"affected":[{"package":{"name":"ruby2.3","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/ruby2.3?arch=source&distro=esm-infra-legacy%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.1-2~ubuntu16.04.16+esm14"}]}],"versions":["2.3.0-1","2.3.0-2","2.3.0-4ubuntu2","2.3.0-4ubuntu3","2.3.0-5ubuntu1","2.3.1-2~16.04","2.3.1-2~16.04.2","2.3.1-2~16.04.4","2.3.1-2~16.04.5","2.3.1-2~16.04.6","2.3.1-2~16.04.7","2.3.1-2~16.04.9","2.3.1-2~16.04.10","2.3.1-2~16.04.11","2.3.1-2~16.04.12","2.3.1-2~ubuntu16.04.13","2.3.1-2~ubuntu16.04.14","2.3.1-2~ubuntu16.04.15","2.3.1-2~ubuntu16.04.16","2.3.1-2~ubuntu16.04.16+esm1","2.3.1-2~ubuntu16.04.16+esm2","2.3.1-2~ubuntu16.04.16+esm3","2.3.1-2~ubuntu16.04.16+esm4","2.3.1-2~ubuntu16.04.16+esm5","2.3.1-2~ubuntu16.04.16+esm6","2.3.1-2~ubuntu16.04.16+esm7","2.3.1-2~ubuntu16.04.16+esm8","2.3.1-2~ubuntu16.04.16+esm9","2.3.1-2~ubuntu16.04.16+esm10","2.3.1-2~ubuntu16.04.16+esm11","2.3.1-2~ubuntu16.04.16+esm12"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro","binaries":[{"binary_version":"2.3.1-2~ubuntu16.04.16+esm14","binary_name":"libruby2.3"},{"binary_version":"2.3.1-2~ubuntu16.04.16+esm14","binary_name":"ruby2.3"},{"binary_version":"2.3.1-2~ubuntu16.04.16+esm14","binary_name":"ruby2.3-tcltk"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8431-1.json","cves_map":{"ecosystem":"Ubuntu:Pro:16.04:LTS","cves":[{"severity":[{"score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","type":"CVSS_V4"},{"score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","type":"CVSS_V3"},{"score":"medium","type":"Ubuntu"}],"id":"CVE-2026-42246"},{"severity":[{"score":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N","type":"CVSS_V4"},{"score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","type":"CVSS_V3"},{"score":"medium","type":"Ubuntu"}],"id":"CVE-2026-42257"}]}}},{"package":{"name":"ruby2.5","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/ruby2.5?arch=source&distro=esm-infra%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.5.1-1ubuntu1.16+esm8"}]}],"versions":["2.5.0~preview1-1ubuntu2","2.5.0-4ubuntu1","2.5.0-4ubuntu4","2.5.0-5ubuntu1","2.5.0-6ubuntu1","2.5.1-1ubuntu1","2.5.1-1ubuntu1.1","2.5.1-1ubuntu1.2","2.5.1-1ubuntu1.4","2.5.1-1ubuntu1.5","2.5.1-1ubuntu1.6","2.5.1-1ubuntu1.7","2.5.1-1ubuntu1.8","2.5.1-1ubuntu1.9","2.5.1-1ubuntu1.10","2.5.1-1ubuntu1.11","2.5.1-1ubuntu1.12","2.5.1-1ubuntu1.13","2.5.1-1ubuntu1.14","2.5.1-1ubuntu1.15","2.5.1-1ubuntu1.16","2.5.1-1ubuntu1.16+esm1","2.5.1-1ubuntu1.16+esm3","2.5.1-1ubuntu1.16+esm4","2.5.1-1ubuntu1.16+esm5","2.5.1-1ubuntu1.16+esm6","2.5.1-1ubuntu1.16+esm7"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro","binaries":[{"binary_version":"2.5.1-1ubuntu1.16+esm8","binary_name":"libruby2.5"},{"binary_version":"2.5.1-1ubuntu1.16+esm8","binary_name":"ruby2.5"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8431-1.json","cves_map":{"ecosystem":"Ubuntu:Pro:18.04:LTS","cves":[{"severity":[{"score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","type":"CVSS_V4"},{"score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","type":"CVSS_V3"},{"score":"medium","type":"Ubuntu"}],"id":"CVE-2026-42246"},{"severity":[{"score":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N","type":"CVSS_V4"},{"score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","type":"CVSS_V3"},{"score":"medium","type":"Ubuntu"}],"id":"CVE-2026-42257"}]}}}],"schema_version":"1.7.5"}