CVE-2026-67194
HIGH
7,1
Source: [email protected]
Attack Vector: network
Attack Complexity: low
Privileges Required: low
User Interaction: none
Confidentiality: N/A
Integrity: N/A
Availability: N/A
MEDIUM
6,5
Source: [email protected]
Attack Vector: network
Attack Complexity: low
Privileges Required: low
User Interaction: none
Scope: unchanged
Confidentiality: none
Integrity: none
Availability: high
Description
AI Translation Available
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.
674
Uncontrolled Recursion
DraftCommon Consequences
Security Scopes Affected:
Availability
Confidentiality
Potential Impacts:
Dos: Resource Consumption (Cpu)
Dos: Resource Consumption (Memory)
Read Application Data
Applicable Platforms
All platforms may be affected
https://github.com/svarshavchik/courier-libs/commit/b5b5581aabea3efadf5e2944947…
https://github.com/svarshavchik/courier/releases/tag/courier%2F2.0.2%2F20260627…
https://github.com/svarshavchik/courier/releases/tag/courier-imap%2F6.0.1%2F202…
https://packages.debian.org/sid/courier-imap
https://www.vulncheck.com/advisories/courier-imap-mail-server-stack-overflow-do…