CVE-2026-67194
MEDIUM SEVERITYCVSS Score & Metrics
Base Score
6.5 / 10
Vector String
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Vulnerability Description
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.
Vulnerability Details
Published Date
Last Modified
CWE ID
CWE-674
Source
NVD
Vendor
svarshavchik
Product
Courier IMAP, Courier Mail Server
External References
- https://github.com/svarshavchik/courier-libs/commit/b5b5581aabea3efadf5e2944947ff0214aa3533e
- https://github.com/svarshavchik/courier/releases/tag/courier%2F2.0.2%2F20260627214309
- https://github.com/svarshavchik/courier/releases/tag/courier-imap%2F6.0.1%2F20260627214444
- https://packages.debian.org/sid/courier-imap
- https://www.vulncheck.com/advisories/courier-imap-mail-server-stack-overflow-dos-via-nested-search-queries
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