{"id":"UBUNTU-CVE-2026-40686","details":"In Exim before 4.99.2, when utf8 operators are enabled, there is an out-of-bounds read if large UTF-8 trailing characters are present (malformed UTF-8 header data). Information might be divulged within an error message produced during handling of an unrelated e-mail message.","modified":"2026-05-14T14:43:00.814594Z","published":"2026-04-29T12:00:00Z","related":["USN-8228-1"],"upstream":["CVE-2026-40686"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-40686"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-40686"},{"type":"REPORT","url":"https://lists.exim.org/lurker/message/20260429.121733.f58d9686.en.html"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8228-1"}],"affected":[{"package":{"name":"exim4","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/exim4@4.82-3ubuntu2.4+esm8?arch=source&distro=esm-infra-legacy/trusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.80-7ubuntu3","4.80-7ubuntu4","4.80-9ubuntu1","4.80-9ubuntu2","4.82-3ubuntu1","4.82-3ubuntu2","4.82-3ubuntu2.1","4.82-3ubuntu2.2","4.82-3ubuntu2.3","4.82-3ubuntu2.4","4.82-3ubuntu2.4+esm1","4.82-3ubuntu2.4+esm2","4.82-3ubuntu2.4+esm3","4.82-3ubuntu2.4+esm4","4.82-3ubuntu2.4+esm6","4.82-3ubuntu2.4+esm7","4.82-3ubuntu2.4+esm8"],"ecosystem_specific":{"binaries":[{"binary_name":"exim4","binary_version":"4.82-3ubuntu2.4+esm8"},{"binary_name":"exim4-base","binary_version":"4.82-3ubuntu2.4+esm8"},{"binary_name":"exim4-config","binary_version":"4.82-3ubuntu2.4+esm8"},{"binary_name":"exim4-daemon-heavy","binary_version":"4.82-3ubuntu2.4+esm8"},{"binary_name":"exim4-daemon-light","binary_version":"4.82-3ubuntu2.4+esm8"},{"binary_name":"eximon4","binary_version":"4.82-3ubuntu2.4+esm8"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40686.json"}},{"package":{"name":"exim4","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/exim4@4.86.2-2ubuntu2.6+esm8?arch=source&distro=esm-infra/xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.86-3ubuntu1","4.86-7ubuntu1","4.86-7ubuntu2","4.86-7ubuntu3","4.86.2-2ubuntu1","4.86.2-2ubuntu2","4.86.2-2ubuntu2.1","4.86.2-2ubuntu2.2","4.86.2-2ubuntu2.3","4.86.2-2ubuntu2.4","4.86.2-2ubuntu2.5","4.86.2-2ubuntu2.6","4.86.2-2ubuntu2.6+esm1","4.86.2-2ubuntu2.6+esm2","4.86.2-2ubuntu2.6+esm4","4.86.2-2ubuntu2.6+esm5","4.86.2-2ubuntu2.6+esm6","4.86.2-2ubuntu2.6+esm7","4.86.2-2ubuntu2.6+esm8"],"ecosystem_specific":{"binaries":[{"binary_name":"exim4","binary_version":"4.86.2-2ubuntu2.6+esm8"},{"binary_name":"exim4-base","binary_version":"4.86.2-2ubuntu2.6+esm8"},{"binary_name":"exim4-config","binary_version":"4.86.2-2ubuntu2.6+esm8"},{"binary_name":"exim4-daemon-heavy","binary_version":"4.86.2-2ubuntu2.6+esm8"},{"binary_name":"exim4-daemon-light","binary_version":"4.86.2-2ubuntu2.6+esm8"},{"binary_name":"eximon4","binary_version":"4.86.2-2ubuntu2.6+esm8"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40686.json"}},{"package":{"name":"exim4","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/exim4@4.90.1-1ubuntu1.10+esm5?arch=source&distro=esm-infra/bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.89-5ubuntu1","4.89-9ubuntu1","4.89-9ubuntu2","4.89-9ubuntu3","4.89-9ubuntu4","4.90.1-1ubuntu1","4.90.1-1ubuntu1.1","4.90.1-1ubuntu1.2","4.90.1-1ubuntu1.3","4.90.1-1ubuntu1.4","4.90.1-1ubuntu1.5","4.90.1-1ubuntu1.8","4.90.1-1ubuntu1.9","4.90.1-1ubuntu1.10","4.90.1-1ubuntu1.10+esm1","4.90.1-1ubuntu1.10+esm2","4.90.1-1ubuntu1.10+esm3","4.90.1-1ubuntu1.10+esm4","4.90.1-1ubuntu1.10+esm5"],"ecosystem_specific":{"binaries":[{"binary_name":"exim4","binary_version":"4.90.1-1ubuntu1.10+esm5"},{"binary_name":"exim4-base","binary_version":"4.90.1-1ubuntu1.10+esm5"},{"binary_name":"exim4-config","binary_version":"4.90.1-1ubuntu1.10+esm5"},{"binary_name":"exim4-daemon-heavy","binary_version":"4.90.1-1ubuntu1.10+esm5"},{"binary_name":"exim4-daemon-light","binary_version":"4.90.1-1ubuntu1.10+esm5"},{"binary_name":"eximon4","binary_version":"4.90.1-1ubuntu1.10+esm5"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40686.json"}},{"package":{"name":"exim4","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/exim4@4.93-13ubuntu1.12?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.92.1-1ubuntu3","4.92.1-1ubuntu4","4.93~RC2-1ubuntu1","4.93-9ubuntu1","4.93-11ubuntu1","4.93-12ubuntu1","4.93-13ubuntu1","4.93-13ubuntu1.1","4.93-13ubuntu1.5","4.93-13ubuntu1.6","4.93-13ubuntu1.7","4.93-13ubuntu1.8","4.93-13ubuntu1.9","4.93-13ubuntu1.10","4.93-13ubuntu1.11","4.93-13ubuntu1.12"],"ecosystem_specific":{"binaries":[{"binary_name":"exim4","binary_version":"4.93-13ubuntu1.12"},{"binary_name":"exim4-base","binary_version":"4.93-13ubuntu1.12"},{"binary_name":"exim4-config","binary_version":"4.93-13ubuntu1.12"},{"binary_name":"exim4-daemon-heavy","binary_version":"4.93-13ubuntu1.12"},{"binary_name":"exim4-daemon-light","binary_version":"4.93-13ubuntu1.12"},{"binary_name":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