{"id":"UBUNTU-CVE-2026-67194","details":"Courier IMAP before 6.0.1 and Courier Mail Server before 2.0.2 allow authenticated IMAP users to crash the imapd process via deeply nested parenthesized SEARCH queries. The SEARCH command parser (alloc_search_key in searchinfo.C) recursively descends on nested parenthesized groups through a mutual recursion chain with alloc_search_andlist() and alloc_search_notkey(), with no depth limit. Courier IMAP has no overall command line length limit, making exploitation trivial. A single IMAP command with ~2500 nested parentheses overflows the 8MB default stack, causing SIGSEGV.","modified":"2026-08-06T03:11:24.357204537Z","published":"2026-07-29T17:16:00Z","upstream":["CVE-2026-67194"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-67194"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-67194"}],"affected":[{"package":{"name":"courier","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/courier?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.68.2-1ubuntu5","0.68.2-1ubuntu6","0.68.2-1ubuntu7"],"ecosystem_specific":{"binaries":[{"binary_name":"courier-base","binary_version":"0.68.2-1ubuntu7"},{"binary_name":"courier-faxmail","binary_version":"0.68.2-1ubuntu7"},{"binary_name":"courier-imap","binary_version":"4.10.0-20120615-1ubuntu7"},{"binary_name":"courier-imap-ssl","binary_version":"4.10.0-20120615-1ubuntu7"},{"binary_name":"courier-ldap","binary_version":"0.68.2-1ubuntu7"},{"binary_name":"courier-maildrop","binary_version":"0.68.2-1ubuntu7"},{"binary_version":"0.68.2-1ubuntu7","binary_name":"courier-mlm"},{"binary_version":"0.68.2-1ubuntu7","binary_name":"courier-mta"},{"binary_name":"courier-mta-ssl","binary_version":"0.68.2-1ubuntu7"},{"binary_version":"0.68.2-1ubuntu7","binary_name":"courier-pcp"},{"binary_name":"courier-pop","binary_version":"0.68.2-1ubuntu7"},{"binary_name":"courier-pop-ssl","binary_version":"0.68.2-1ubuntu7"},{"binary_name":"courier-ssl","binary_version":"0.68.2-1ubuntu7"},{"binary_name":"courier-webadmin","binary_version":"0.68.2-1ubuntu7"},{"binary_name":"sqwebmail","binary_version":"0.68.2-1ubuntu7"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-67194.json"}},{"package":{"name":"courier","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/courier?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.78.0-2","0.78.0-2ubuntu1","0.78.0-2ubuntu2"],"ecosystem_specific":{"binaries":[{"binary_name":"courier-base","binary_version":"0.78.0-2ubuntu2"},{"binary_name":"courier-faxmail","binary_version":"0.78.0-2ubuntu2"},{"binary_name":"courier-imap","binary_version":"4.18.1+0.78.0-2ubuntu2"},{"binary_name":"courier-imap-ssl","binary_version":"4.18.1+0.78.0-2ubuntu2"},{"binary_name":"courier-ldap","binary_version":"0.78.0-2ubuntu2"},{"binary_version":"2.9.1+0.78.0-2ubuntu2","binary_name":"courier-maildrop"},{"binary_name":"courier-mlm","binary_version":"0.78.0-2ubuntu2"},{"binary_name":"courier-mta","binary_version":"0.78.0-2ubuntu2"},{"binary_version":"0.78.0-2ubuntu2","binary_name":"courier-mta-ssl"},{"binary_version":"0.78.0-2ubuntu2","binary_name":"courier-pcp"},{"binary_version":"0.78.0-2ubuntu2","binary_name":"courier-pop"},{"binary_name":"courier-pop-ssl","binary_version":"0.78.0-2ubuntu2"},{"binary_name":"courier-ssl","binary_version":"0.78.0-2ubuntu2"},{"binary_name":"courier-webadmin","binary_version":"0.78.0-2ubuntu2"},{"binary_name":"sqwebmail","binary_version":"5.9.0+0.78.0-2ubuntu2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-67194.json"}},{"package":{"name":"courier","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/courier?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.6-1build1","1.0.6-1build2"],"ecosystem_specific":{"binaries":[{"binary_name":"courier-base","binary_version":"1.0.6-1build2"},{"binary_name":"courier-faxmail","binary_version":"1.0.6-1build2"},{"binary_name":"courier-imap","binary_version":"5.0.6+1.0.6-1build2"},{"binary_name":"courier-ldap","binary_version":"1.0.6-1build2"},{"binary_name":"courier-mlm","binary_version":"1.0.6-1build2"},{"binary_version":"1.0.6-1build2","binary_name":"courier-mta"},{"binary_version":"1.0.6-1build2","binary_name":"courier-pcp"},{"binary_version":"1.0.6-1build2","binary_name":"courier-pop"},{"binary_name":"courier-webadmin","binary_version":"1.0.6-1build2"},{"binary_name":"sqwebmail","binary_version":"6.0.0+1.0.6-1build2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-67194.json"}},{"package":{"name":"courier","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/courier?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.16-3build1","1.0.16-3build2","1.0.16-3build3"],"ecosystem_specific":{"binaries":[{"binary_name":"courier-base","binary_version":"1.0.16-3build3"},{"binary_version":"1.0.16-3build3","binary_name":"courier-faxmail"},{"binary_version":"5.0.13+1.0.16-3build3","binary_name":"courier-imap"},{"binary_name":"courier-ldap","binary_version":"1.0.16-3build3"},{"binary_name":"courier-mlm","binary_version":"1.0.16-3build3"},{"binary_version":"1.0.16-3build3","binary_name":"courier-mta"},{"binary_name":"courier-pcp","binary_version":"1.0.16-3build3"},{"binary_name":"courier-pop","binary_version":"1.0.16-3build3"},{"binary_name":"courier-webadmin","binary_version":"1.0.16-3build3"},{"binary_version":"6.0.5+1.0.16-3build3","binary_name":"sqwebmail"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-67194.json"}},{"package":{"name":"courier","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/courier?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.4.1-3","1.4.1-10","1.5.1-2"],"ecosystem_specific":{"binaries":[{"binary_name":"courier-base","binary_version":"1.5.1-2"},{"binary_version":"1.5.1-2","binary_name":"courier-faxmail"},{"binary_name":"courier-imap","binary_version":"5.3.1+1.5.1-2"},{"binary_version":"1.5.1-2","binary_name":"courier-ldap"},{"binary_version":"1.5.1-2","binary_name":"courier-mlm"},{"binary_name":"courier-mta","binary_version":"1.5.1-2"},{"binary_name":"courier-pcp","binary_version":"1.5.1-2"},{"binary_name":"courier-pop","binary_version":"1.5.1-2"},{"binary_name":"courier-webadmin","binary_version":"1.5.1-2"},{"binary_version":"6.3.1+1.5.1-2","binary_name":"sqwebmail"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-67194.json"}}],"schema_version":"1.8.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}