{"id":"DEBIAN-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":"2026-09-14T17:03:29.040890676Z","published":"2026-07-29T17:16:54.017Z","upstream":["CVE-2026-67194"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-67194"}],"affected":[{"package":{"name":"courier","ecosystem":"Debian:12","purl":"pkg:deb/debian/courier?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.16-3","1.0.16-3.1","1.0.16-3.2","1.3.13-1","1.3.13-10","1.3.13-11","1.3.13-2","1.3.13-3","1.3.13-4","1.3.13-5","1.3.13-6","1.3.13-7","1.3.13-8","1.3.13-9","1.4.1-1","1.4.1-10","1.4.1-2","1.4.1-3","1.4.1-4","1.4.1-5","1.4.1-6","1.4.1-7","1.4.1-8","1.4.1-9","1.5.1-1","1.5.1-2","1.5.1-3","1.5.1-4","2.0.2-1","2.0.2-2","2.0.2-3","2.0.2-4","2.0.3-1","2.0.3-2","2.0.6-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-67194.json"}},{"package":{"name":"courier","ecosystem":"Debian:13","purl":"pkg:deb/debian/courier?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.4.1-10","1.4.1-3","1.4.1-3+deb13u1","1.4.1-3+deb13u2","1.4.1-4","1.4.1-5","1.4.1-6","1.4.1-7","1.4.1-8","1.4.1-9","1.5.1-1","1.5.1-2","1.5.1-3","1.5.1-4","2.0.2-1","2.0.2-2","2.0.2-3","2.0.2-4","2.0.3-1","2.0.3-2","2.0.6-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-67194.json"}},{"package":{"name":"courier","ecosystem":"Debian:14","purl":"pkg:deb/debian/courier?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.3-1"}]}],"versions":["1.4.1-10","1.4.1-3","1.4.1-4","1.4.1-5","1.4.1-6","1.4.1-7","1.4.1-8","1.4.1-9","1.5.1-1","1.5.1-2","1.5.1-3","1.5.1-4","2.0.2-1","2.0.2-2","2.0.2-3","2.0.2-4"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-67194.json"}}],"schema_version":"1.9.0","severity":[{"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"}]}