CVE Catalog

CVE-2026-67194

MediumCVSS 6.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.31%

23th percentile - higher than 23% of all known CVEs

Summary

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 recursively descends without depth limit, and no command line length limit makes exploitation trivial; about 2500 nested parentheses cause stack overflow and SIGSEGV.

Risk Assessment

An authenticated attacker can crash the mail server, leading to denial of service (DoS) and potential loss of email messages.

Recommendation

Update Courier IMAP to version 6.0.1 or later and Courier Mail Server to version 2.0.2 or later.

Related vulnerabilities

Original NVD description (English source)

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 data from NVD (NIST) · CISA KEV · EPSS