courier: Courier IMAP before 6.0.1 and Courier Mail Server before 2.0.2 allow authenticated IMAP users to crash the imapd proc...
CVE-2026-67194 is fixed in courier on 1 platform by DEBIAN-CVE-2026-67194 (version 2.0.3-1), released July 31, 2026. It is not reported as exploited. Patch Radar priority: Routine.
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| courier · Debian 14 | 2.0.3-1 | DEBIAN-CVE-2026-67194 | Jul 31, 2026 |
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