{"id":"UBUNTU-CVE-2026-63435","details":"Mail is an internet library for Ruby designed to handle email generation, parsing, and sending. Prior to 2.9.1, Mail::Utilities.q_value_decode and Mail::Utilities.b_value_decode used a single String#match and an overly greedy charset capture to decode only the first RFC 2047 encoded-word and mishandle surrounding or subsequent text. A crafted malformed encoded-word in an address display name or local part could cross ? delimiters and make decoded From, To, or Reply-To header values differ from the raw values inspected by a human reviewer or downstream parser, enabling apparent sender or recipient spoofing, phishing, or authorization-check bypass. This issue is fixed in version 2.9.1.","modified":"2026-09-16T14:01:52.188507615Z","published":"2026-09-01T21:18:00Z","upstream":["CVE-2026-63435"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-63435"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-63435"}],"affected":[{"package":{"name":"jruby","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/jruby?arch=source&distro=esm-infra-legacy%2Ftrusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.5.6-5ubuntu1","1.5.6-6","1.5.6-7","1.5.6-9+deb8u2build0.14.04.1~esm2"],"ecosystem_specific":{"binaries":[{"binary_name":"jruby","binary_version":"1.5.6-9+deb8u2build0.14.04.1~esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63435.json"}},{"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"}]}],"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","2.3.1-2~ubuntu16.04.16+esm14","2.3.1-2~ubuntu16.04.16+esm15"],"ecosystem_specific":{"binaries":[{"binary_name":"libruby2.3","binary_version":"2.3.1-2~ubuntu16.04.16+esm15"},{"binary_version":"2.3.1-2~ubuntu16.04.16+esm15","binary_name":"ruby2.3"},{"binary_name":"ruby2.3-tcltk","binary_version":"2.3.1-2~ubuntu16.04.16+esm15"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63435.json"}},{"package":{"name":"jruby","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/jruby?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.7.21-2ubuntu4","1.7.22-1ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_name":"jruby","binary_version":"1.7.22-1ubuntu1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63435.json"}},{"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"}]}],"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","2.5.1-1ubuntu1.16+esm8"],"ecosystem_specific":{"binaries":[{"binary_name":"libruby2.5","binary_version":"2.5.1-1ubuntu1.16+esm8"},{"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/cve/2026/UBUNTU-CVE-2026-63435.json"}},{"package":{"name":"jruby","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/jruby?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["9.1.13.0-1","9.1.17.0-1~18.04"],"ecosystem_specific":{"binaries":[{"binary_name":"jruby","binary_version":"9.1.17.0-1~18.04"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63435.json"}},{"package":{"name":"ruby2.7","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/ruby2.7?arch=source&distro=esm-infra%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.7.0-1","2.7.0-2","2.7.0-3","2.7.0-4","2.7.0-4ubuntu1","2.7.0-5ubuntu1","2.7.0-5ubuntu1.1","2.7.0-5ubuntu1.2","2.7.0-5ubuntu1.3","2.7.0-5ubuntu1.4","2.7.0-5ubuntu1.5","2.7.0-5ubuntu1.6","2.7.0-5ubuntu1.7","2.7.0-5ubuntu1.8","2.7.0-5ubuntu1.9","2.7.0-5ubuntu1.10","2.7.0-5ubuntu1.11","2.7.0-5ubuntu1.12","2.7.0-5ubuntu1.13","2.7.0-5ubuntu1.14","2.7.0-5ubuntu1.15","2.7.0-5ubuntu1.16","2.7.0-5ubuntu1.17","2.7.0-5ubuntu1.18","2.7.0-5ubuntu1.18+esm1","2.7.0-5ubuntu1.18+esm3","2.7.0-5ubuntu1.18+esm4","2.7.0-5ubuntu1.18+esm5"],"ecosystem_specific":{"binaries"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