CVE-2026-67194
Received
Received - Intake
Authenticated IMAP Command Injection in Courier Mail Server
Vulnerability report for CVE-2026-67194, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-07-29
Last updated on: 2026-07-29
Assigner: VulnCheck
Description
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.
CVSS Scores
EPSS Scores
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| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| courier | mta | to 6.0.1 (exc) |
| courier | mail_server | to 2.0.2 (exc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-674 | The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack. |
