High
courier — security advisory
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.
- Products
- courier
- Affected versions
- 0.68.2-1ubuntu5, 0.68.2-1ubuntu6, 0.68.2-1ubuntu7, 0.78.0-2, 0.78.0-2ubuntu1, 0.78.0-2ubuntu2, 1.0.16-3build1, 1.0.16-3build2, 1.0.16-3build3, 1.0.6-1build1, 1.0.6-1build2, 1.4.1-10, 1.4.1-3, 1.5.1-2, 1.5.1-4, 2.0.6-1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-67194
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:50 UTC · Revision 1
Source evidence
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.
osv:UBUNTU-CVE-2026-67194
courier
Fixed versions: Not specified
courier
Fixed versions: Not specified
courier
Fixed versions: Not specified
courier
Fixed versions: Not specified
courier
Fixed versions: Not specified
courier
Fixed versions: Not specified
Complete source record
{
"id": "4a0151a8fad70a3fa445c3fd77a1ed794d303ecd5fa132ba96f64f425539b0b1",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-67194",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-67194",
"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 (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.",
"evidence": "osv:UBUNTU-CVE-2026-67194",
"products": [
{
"name": {
"value": "courier",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.68.2-1ubuntu5",
"evidence": "/affected/0/versions"
},
{
"value": "0.68.2-1ubuntu6",
"evidence": "/affected/0/versions"
},
{
"value": "0.68.2-1ubuntu7",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "courier",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.78.0-2",
"evidence": "/affected/1/versions"
},
{
"value": "0.78.0-2ubuntu1",
"evidence": "/affected/1/versions"
},
{
"value": "0.78.0-2ubuntu2",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "courier",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.0.6-1build1",
"evidence": "/affected/2/versions"
},
{
"value": "1.0.6-1build2",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "courier",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.0.16-3build1",
"evidence": "/affected/3/versions"
},
{
"value": "1.0.16-3build2",
"evidence": "/affected/3/versions"
},
{
"value": "1.0.16-3build3",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "courier",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.5.1-2",
"evidence": "/affected/4/versions"
},
{
"value": "1.5.1-4",
"evidence": "/affected/4/versions"
},
{
"value": "2.0.6-1",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "courier",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.4.1-3",
"evidence": "/affected/5/versions"
},
{
"value": "1.4.1-10",
"evidence": "/affected/5/versions"
},
{
"value": "1.5.1-2",
"evidence": "/affected/5/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2026-67194",
"aliases": [
"UBUNTU-CVE-2026-67194"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
},
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "courier",
"purl": "pkg:deb/ubuntu/courier?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"0.68.2-1ubuntu5",
"0.68.2-1ubuntu6",
"0.68.2-1ubuntu7"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-67194.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "courier-base",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-faxmail",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-imap",
"binary_version": "4.10.0-20120615-1ubuntu7"
},
{
"binary_name": "courier-imap-ssl",
"binary_version": "4.10.0-20120615-1ubuntu7"
},
{
"binary_name": "courier-ldap",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-maildrop",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-mlm",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-mta",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-mta-ssl",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-pcp",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-pop",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-pop-ssl",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-ssl",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-webadmin",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "sqwebmail",
"binary_version": "0.68.2-1ubuntu7"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "courier",
"purl": "pkg:deb/ubuntu/courier?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
"0.78.0-2",
"0.78.0-2ubuntu1",
"0.78.0-2ubuntu2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-67194.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "courier-base",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-faxmail",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-imap",
"binary_version": "4.18.1+0.78.0-2ubuntu2"
},
{
"binary_name": "courier-imap-ssl",
"binary_version": "4.18.1+0.78.0-2ubuntu2"
},
{
"binary_name": "courier-ldap",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-maildrop",
"binary_version": "2.9.1+0.78.0-2ubuntu2"
},
{
"binary_name": "courier-mlm",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-mta",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-mta-ssl",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-pcp",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-pop",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-pop-ssl",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-ssl",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-webadmin",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "sqwebmail",
"binary_version": "5.9.0+0.78.0-2ubuntu2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "courier",
"purl": "pkg:deb/ubuntu/courier?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
"1.0.6-1build1",
"1.0.6-1build2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-67194.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "courier-base",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "courier-faxmail",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "courier-imap",
"binary_version": "5.0.6+1.0.6-1build2"
},
{
"binary_name": "courier-ldap",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "courier-mlm",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "courier-mta",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "courier-pcp",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "courier-pop",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "courier-webadmin",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "sqwebmail",
"binary_version": "6.0.0+1.0.6-1build2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "courier",
"purl": "pkg:deb/ubuntu/courier?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"1.0.16-3build1",
"1.0.16-3build2",
"1.0.16-3build3"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-67194.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "courier-base",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "courier-faxmail",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "courier-imap",
"binary_version": "5.0.13+1.0.16-3build3"
},
{
"binary_name": "courier-ldap",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "courier-mlm",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "courier-mta",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "courier-pcp",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "courier-pop",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "courier-webadmin",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "sqwebmail",
"binary_version": "6.0.5+1.0.16-3build3"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "courier",
"purl": "pkg:deb/ubuntu/courier?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"1.5.1-2",
"1.5.1-4",
"2.0.6-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-67194.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "courier-base",
"binary_version": "2.0.6-1"
},
{
"binary_name": "courier-faxmail",
"binary_version": "2.0.6-1"
},
{
"binary_name": "courier-imap",
"binary_version": "6.0.5+2.0.6-1"
},
{
"binary_name": "courier-ldap",
"binary_version": "2.0.6-1"
},
{
"binary_name": "courier-mlm",
"binary_version": "2.0.6-1"
},
{
"binary_name": "courier-mta",
"binary_version": "2.0.6-1"
},
{
"binary_name": "courier-pcp",
"binary_version": "2.0.6-1"
},
{
"binary_name": "courier-pop",
"binary_version": "2.0.6-1"
},
{
"binary_name": "courier-webadmin",
"binary_version": "2.0.6-1"
},
{
"binary_name": "sqwebmail",
"binary_version": "7.0.4+2.0.6-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "courier",
"purl": "pkg:deb/ubuntu/courier?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"1.4.1-3",
"1.4.1-10",
"1.5.1-2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-67194.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "courier-base",
"binary_version": "1.5.1-2"
},
{
"binary_name": "courier-faxmail",
"binary_version": "1.5.1-2"
},
{
"binary_name": "courier-imap",
"binary_version": "5.3.1+1.5.1-2"
},
{
"binary_name": "courier-ldap",
"binary_version": "1.5.1-2"
},
{
"binary_name": "courier-mlm",
"binary_version": "1.5.1-2"
},
{
"binary_name": "courier-mta",
"binary_version": "1.5.1-2"
},
{
"binary_name": "courier-pcp",
"binary_version": "1.5.1-2"
},
{
"binary_name": "courier-pop",
"binary_version": "1.5.1-2"
},
{
"binary_name": "courier-webadmin",
"binary_version": "1.5.1-2"
},
{
"binary_name": "sqwebmail",
"binary_version": "6.3.1+1.5.1-2"
}
]
}
}
],
"modified": "2026-10-17T12:59:19.002049429Z",
"provider": "osv",
"upstream": [
"CVE-2026-67194"
],
"references": [
"https://ubuntu.com/security/CVE-2026-67194",
"https://www.cve.org/CVERecord?id=CVE-2026-67194"
]
},
"related_cves": [
{
"value": "CVE-2026-67194",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/1/score"
},
"source_id": "core-osv",
"document_id": 359618,
"published_at": "2026-07-29T17:16:00+00:00"
}