Answer in brief
CVE-2026-67194 records a High severity (CVSS 7.1) vulnerability in Courier IMAP < 6.0.1 Mail Server < 2.0.2 Stack Overflow DoS via Nested SEARCH Queries. The current sources do not mark it as known exploited. The current feed maps svarshavchik/Courier IMAP (generic), svarshavchik/Courier IMAP (generic), svarshavchik/Courier Mail Server (generic), svarshavchik/Courier Mail Server (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps svarshavchik/Courier IMAP (generic), svarshavchik/Courier IMAP (generic), svarshavchik/Courier Mail Server (generic), svarshavchik/Courier Mail Server (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| svarshavchik/Courier IMAPgeneric | >=0 <6.0.1 | 6.0.1 |
| svarshavchik/Courier IMAPgeneric | * | Not reported |
| svarshavchik/Courier Mail Servergeneric | >=0 <2.0.2 | 2.0.2 |
| svarshavchik/Courier Mail Servergeneric | * | Not reported |
Published upstream
Jul 29, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 14, 2026
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.
Quoted source text, attributed separately from HOL analysis.