Courier IMAP Search Command Parser searchinfo.C alloc_search_key recursion

CVSS Meta Temp Score
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CTI Interest Score
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6.2$0-$5k1.70

Summaryinfo

A vulnerability was found in Courier IMAP. It has been rated as critical. This issue affects the function alloc_search_key of the file searchinfo.C of the component Search Command Parser. This manipulation causes recursion. This vulnerability appears as CVE-2026-67194. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability has been found in Courier IMAP (version unknown) and classified as critical. Affected by this vulnerability is the function alloc_search_key of the file searchinfo.C of the component Search Command Parser. The manipulation with an unknown input leads to a recursion vulnerability. The CWE definition for the vulnerability is 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. As an impact it is known to affect availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-67194 since 07/28/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Applying the patch 6.0.1 is able to eliminate this problem.

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Productinfo

Name

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.2

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Recursion
CWE: CWE-674 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔒

Patch: 6.0.1

Timelineinfo

07/28/2026 CVE reserved
07/29/2026 +1 days Advisory disclosed
07/29/2026 +0 days VulDB entry created
07/29/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-67194 (🔒)
GCVE (CVE): GCVE-0-2026-67194
GCVE (VulDB): GCVE-100-384223

Entryinfo

Created: 07/29/2026 19:19
Changes: 07/29/2026 19:19 (55)
Complete: 🔍
Cache ID: 216::103

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