UBUNTU-CVE-2026-40017

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Source
https://ubuntu.com/security/CVE-2026-40017
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40017.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-40017
Upstream
  • CVE-2026-40017
Published
2026-08-28T00:00:00Z
Modified
2026-09-02T19:36:04Z
Severity
  • 6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

An attacker that can send mail to a user can craft a message header whose values are chosen to collide in an internal hash table, which makes the IMAP THREAD command consume CPU disproportionate to the size of the message. This is a separate issue from CVE-2026-40014 and is not addressed by that fix. Whenever a mail client issues a THREAD command on the affected mailbox, this can cause degradation or denial of service for IMAP. Monitor system for abnormal CPU usage, kill the offending process and remove the offending message from the affected mailbox. Update to non-vulnerable version. No publicly available exploits are known.

References

Affected packages

Ubuntu:16.04:LTS
dovecot

Package

Name
dovecot
Purl
pkg:deb/ubuntu/dovecot?arch=source&distro=xenial

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:2.*
1:2.2.18-2ubuntu2
1:2.2.22-1ubuntu1
1:2.2.22-1ubuntu2
1:2.2.22-1ubuntu2.1
1:2.2.22-1ubuntu2.2
1:2.2.22-1ubuntu2.3
1:2.2.22-1ubuntu2.4
1:2.2.22-1ubuntu2.6
1:2.2.22-1ubuntu2.7
1:2.2.22-1ubuntu2.8
1:2.2.22-1ubuntu2.9
1:2.2.22-1ubuntu2.10
1:2.2.22-1ubuntu2.11
1:2.2.22-1ubuntu2.12
1:2.2.22-1ubuntu2.13
1:2.2.22-1ubuntu2.14

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "dovecot-core",
            "binary_version":  "1:2.2.22-1ubuntu2.14"
        },
        {
            "binary_name":  "dovecot-gssapi",
            "binary_version":  "1:2.2.22-1ubuntu2.14"
        },
        {
            "binary_name":  "dovecot-imapd",
            "binary_version":  "1:2.2.22-1ubuntu2.14"
        },
        {
            "binary_name":  "dovecot-ldap",
            "binary_version":  "1:2.2.22-1ubuntu2.14"
        },
        {
            "binary_name":  "dovecot-lmtpd",
            "binary_version":  "1:2.2.22-1ubuntu2.14"
        },
        {
            "binary_name":  "dovecot-lucene",
            "binary_version":  "1:2.2.22-1ubuntu2.14"
        },
        {
            "binary_name":  "dovecot-managesieved",
            "binary_version":  "1:2.2.22-1ubuntu2.14"
        },
        {
            "binary_name":  "dovecot-mysql",
            "binary_version":  "1:2.2.22-1ubuntu2.14"
        },
        {
            "binary_name":  "dovecot-pgsql",
            "binary_version":  "1:2.2.22-1ubuntu2.14"
        },
        {
            "binary_name":  "dovecot-pop3d",
            "binary_version":  "1:2.2.22-1ubuntu2.14"
        },
        {
            "binary_name":  "dovecot-sieve",
            "binary_version":  "1:2.2.22-1ubuntu2.14"
        },
        {
            "binary_name":  "dovecot-solr",
            "binary_version":  "1:2.2.22-1ubuntu2.14"
        },
        {
            "binary_name":  "dovecot-sqlite",
            "binary_version":  "1:2.2.22-1ubuntu2.14"
        },
        {
            "binary_name":  "mail-stack-delivery",
            "binary_version":  "1:2.2.22-1ubuntu2.14"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40017.json"
Ubuntu:18.04:LTS
dovecot

Package

Name
dovecot
Purl
pkg:deb/ubuntu/dovecot?arch=source&distro=bionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:2.*
1:2.2.27-3ubuntu1
1:2.2.33.2-1ubuntu1
1:2.2.33.2-1ubuntu2
1:2.2.33.2-1ubuntu3
1:2.2.33.2-1ubuntu4
1:2.2.33.2-1ubuntu4.1
1:2.2.33.2-1ubuntu4.2
1:2.2.33.2-1ubuntu4.3
1:2.2.33.2-1ubuntu4.4
1:2.2.33.2-1ubuntu4.5
1:2.2.33.2-1ubuntu4.6
1:2.2.33.2-1ubuntu4.7
1:2.2.33.2-1ubuntu4.8

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "dovecot-core",
            "binary_version":  "1:2.2.33.2-1ubuntu4.8"
        },
        {
            "binary_name":  "dovecot-gssapi",
            "binary_version":  "1:2.2.33.2-1ubuntu4.8"
        },
        {
            "binary_name":  "dovecot-imapd",
            "binary_version":  "1:2.2.33.2-1ubuntu4.8"
        },
        {
            "binary_name":  "dovecot-ldap",
            "binary_version":  "1:2.2.33.2-1ubuntu4.8"
        },
        {
            "binary_name":  "dovecot-lmtpd",
            "binary_version":  "1:2.2.33.2-1ubuntu4.8"
        },
        {
            "binary_name":  "dovecot-managesieved",
            "binary_version":  "1:2.2.33.2-1ubuntu4.8"
        },
        {
            "binary_name":  "dovecot-mysql",
            "binary_version":  "1:2.2.33.2-1ubuntu4.8"
        },
        {
            "binary_name":  "dovecot-pgsql",
            "binary_version":  "1:2.2.33.2-1ubuntu4.8"
        },
        {
            "binary_name":  "dovecot-pop3d",
            "binary_version":  "1:2.2.33.2-1ubuntu4.8"
        },
        {
            "binary_name":  "dovecot-sieve",
            "binary_version":  "1:2.2.33.2-1ubuntu4.8"
        },
        {
            "binary_name":  "dovecot-solr",
            "binary_version":  "1:2.2.33.2-1ubuntu4.8"
        },
        {
            "binary_name":  "dovecot-sqlite",
            "binary_version":  "1:2.2.33.2-1ubuntu4.8"
        },
        {
            "binary_name":  "mail-stack-delivery",
            "binary_version":  "1:2.2.33.2-1ubuntu4.8"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40017.json"
Ubuntu:20.04:LTS
dovecot

Package

Name
dovecot
Purl
pkg:deb/ubuntu/dovecot?arch=source&distro=focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:2.*
1:2.3.4.1-5ubuntu3
1:2.3.7.2-1ubuntu1
1:2.3.7.2-1ubuntu2
1:2.3.7.2-1ubuntu3
1:2.3.7.2-1ubuntu3.1
1:2.3.7.2-1ubuntu3.2
1:2.3.7.2-1ubuntu3.3
1:2.3.7.2-1ubuntu3.4
1:2.3.7.2-1ubuntu3.5
1:2.3.7.2-1ubuntu3.6
1:2.3.7.2-1ubuntu3.7

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "dovecot-auth-lua",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "dovecot-core",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "dovecot-gssapi",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "dovecot-imapd",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "dovecot-ldap",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "dovecot-lmtpd",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "dovecot-lucene",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "dovecot-managesieved",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "dovecot-mysql",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "dovecot-pgsql",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "dovecot-pop3d",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "dovecot-sieve",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "dovecot-solr",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "dovecot-sqlite",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "dovecot-submissiond",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        },
        {
            "binary_name":  "mail-stack-delivery",
            "binary_version":  "1:2.3.7.2-1ubuntu3.7"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40017.json"
Ubuntu:22.04:LTS
dovecot

Package

Name
dovecot
Purl
pkg:deb/ubuntu/dovecot?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:2.*
1:2.3.13+dfsg1-1ubuntu3
1:2.3.16+dfsg1-3ubuntu1
1:2.3.16+dfsg1-3ubuntu2
1:2.3.16+dfsg1-3ubuntu2.1
1:2.3.16+dfsg1-3ubuntu2.2
1:2.3.16+dfsg1-3ubuntu2.4
1:2.3.16+dfsg1-3ubuntu2.6
1:2.3.16+dfsg1-3ubuntu2.7
1:2.3.16+dfsg1-3ubuntu2.8
1:2.3.16+dfsg1-3ubuntu2.9

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "dovecot-auth-lua",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        },
        {
            "binary_name":  "dovecot-core",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        },
        {
            "binary_name":  "dovecot-gssapi",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        },
        {
            "binary_name":  "dovecot-imapd",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        },
        {
            "binary_name":  "dovecot-ldap",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        },
        {
            "binary_name":  "dovecot-lmtpd",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        },
        {
            "binary_name":  "dovecot-lucene",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        },
        {
            "binary_name":  "dovecot-managesieved",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        },
        {
            "binary_name":  "dovecot-mysql",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        },
        {
            "binary_name":  "dovecot-pgsql",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        },
        {
            "binary_name":  "dovecot-pop3d",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        },
        {
            "binary_name":  "dovecot-sieve",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        },
        {
            "binary_name":  "dovecot-solr",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        },
        {
            "binary_name":  "dovecot-sqlite",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        },
        {
            "binary_name":  "dovecot-submissiond",
            "binary_version":  "1:2.3.16+dfsg1-3ubuntu2.9"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40017.json"
Ubuntu:24.04:LTS
dovecot

Package

Name
dovecot
Purl
pkg:deb/ubuntu/dovecot?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:2.*
1:2.3.20+dfsg1-1ubuntu3
1:2.3.21+dfsg1-2ubuntu1
1:2.3.21+dfsg1-2ubuntu2
1:2.3.21+dfsg1-2ubuntu4
1:2.3.21+dfsg1-2ubuntu5
1:2.3.21+dfsg1-2ubuntu6
1:2.3.21+dfsg1-2ubuntu6.1
1:2.3.21+dfsg1-2ubuntu6.2
1:2.3.21+dfsg1-2ubuntu6.3
1:2.3.21+dfsg1-2ubuntu6.4
1:2.3.21+dfsg1-2ubuntu6.5

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "dovecot-auth-lua",
            "binary_version":  "1:2.3.21+dfsg1-2ubuntu6.5"
        },
        {
            "binary_name":  "dovecot-core",
            "binary_version":  "1:2.3.21+dfsg1-2ubuntu6.5"
        },
        {
            "binary_name":  "dovecot-gssapi",
            "binary_version":  "1:2.3.21+dfsg1-2ubuntu6.5"
        },
        {
            "binary_name":  "dovecot-imapd",
            "binary_version":  "1:2.3.21+dfsg1-2ubuntu6.5"
        },
        {
            "binary_name":  "dovecot-ldap",
            "binary_version":  "1:2.3.21+dfsg1-2ubuntu6.5"
        },
        {
            "binary_name":  "dovecot-lmtpd",
            "binary_version":  "1:2.3.21+dfsg1-2ubuntu6.5"
        },
        {
            "binary_name":  "dovecot-managesieved",
            "binary_version":  "1:2.3.21+dfsg1-2ubuntu6.5"
        },
        {
            "binary_name":  "dovecot-mysql",
            "binary_version":  "1:2.3.21+dfsg1-2ubuntu6.5"
        },
        {
            "binary_name":  "dovecot-pgsql",
            "binary_version":  "1:2.3.21+dfsg1-2ubuntu6.5"
        },
        {
            "binary_name":  "dovecot-pop3d",
            "binary_version":  "1:2.3.21+dfsg1-2ubuntu6.5"
        },
        {
            "binary_name":  "dovecot-sieve",
            "binary_version":  "1:2.3.21+dfsg1-2ubuntu6.5"
        },
        {
            "binary_name":  "dovecot-solr",
            "binary_version":  "1:2.3.21+dfsg1-2ubuntu6.5"
        },
        {
            "binary_name":  "dovecot-sqlite",
            "binary_version":  "1:2.3.21+dfsg1-2ubuntu6.5"
        },
        {
            "binary_name":  "dovecot-submissiond",
            "binary_version":  "1:2.3.21+dfsg1-2ubuntu6.5"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40017.json"
Ubuntu:26.04:LTS
dovecot

Package

Name
dovecot
Purl
pkg:deb/ubuntu/dovecot?arch=source&distro=resolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:2.*
1:2.4.1+dfsg1-5ubuntu4
1:2.4.1+dfsg1-5ubuntu5
1:2.4.2+dfsg1-3ubuntu1
1:2.4.2+dfsg1-3ubuntu2
1:2.4.2+dfsg1-3ubuntu2.1

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "dovecot-auth-lua",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        },
        {
            "binary_name":  "dovecot-core",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        },
        {
            "binary_name":  "dovecot-flatcurve",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        },
        {
            "binary_name":  "dovecot-gssapi",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        },
        {
            "binary_name":  "dovecot-imapd",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        },
        {
            "binary_name":  "dovecot-ldap",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        },
        {
            "binary_name":  "dovecot-lmtpd",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        },
        {
            "binary_name":  "dovecot-managesieved",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        },
        {
            "binary_name":  "dovecot-mysql",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        },
        {
            "binary_name":  "dovecot-pgsql",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        },
        {
            "binary_name":  "dovecot-pop3d",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        },
        {
            "binary_name":  "dovecot-sieve",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        },
        {
            "binary_name":  "dovecot-solr",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        },
        {
            "binary_name":  "dovecot-sqlite",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        },
        {
            "binary_name":  "dovecot-submissiond",
            "binary_version":  "1:2.4.2+dfsg1-3ubuntu2.1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40017.json"
Ubuntu:Pro:14.04:LTS
dovecot

Package

Name
dovecot
Purl
pkg:deb/ubuntu/dovecot?arch=source&distro=esm-infra-legacy%2Ftrusty

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:2.*
1:2.1.7-7ubuntu3
1:2.2.9-1ubuntu1
1:2.2.9-1ubuntu2
1:2.2.9-1ubuntu2.1
1:2.2.9-1ubuntu2.3
1:2.2.9-1ubuntu2.4
1:2.2.9-1ubuntu2.5
1:2.2.9-1ubuntu2.6
1:2.2.9-1ubuntu2.6+esm1
1:2.2.9-1ubuntu2.6+esm2
1:2.2.9-1ubuntu2.6+esm3
1:2.2.9-1ubuntu2.6+esm4

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "dovecot-core",
            "binary_version":  "1:2.2.9-1ubuntu2.6+esm4"
        },
        {
            "binary_name":  "dovecot-gssapi",
            "binary_version":  "1:2.2.9-1ubuntu2.6+esm4"
        },
        {
            "binary_name":  "dovecot-imapd",
            "binary_version":  "1:2.2.9-1ubuntu2.6+esm4"
        },
        {
            "binary_name":  "dovecot-ldap",
            "binary_version":  "1:2.2.9-1ubuntu2.6+esm4"
        },
        {
            "binary_name":  "dovecot-lmtpd",
            "binary_version":  "1:2.2.9-1ubuntu2.6+esm4"
        },
        {
            "binary_name":  "dovecot-managesieved",
            "binary_version":  "1:2.2.9-1ubuntu2.6+esm4"
        },
        {
            "binary_name":  "dovecot-mysql",
            "binary_version":  "1:2.2.9-1ubuntu2.6+esm4"
        },
        {
            "binary_name":  "dovecot-pgsql",
            "binary_version":  "1:2.2.9-1ubuntu2.6+esm4"
        },
        {
            "binary_name":  "dovecot-pop3d",
            "binary_version":  "1:2.2.9-1ubuntu2.6+esm4"
        },
        {
            "binary_name":  "dovecot-sieve",
            "binary_version":  "1:2.2.9-1ubuntu2.6+esm4"
        },
        {
            "binary_name":  "dovecot-solr",
            "binary_version":  "1:2.2.9-1ubuntu2.6+esm4"
        },
        {
            "binary_name":  "dovecot-sqlite",
            "binary_version":  "1:2.2.9-1ubuntu2.6+esm4"
        },
        {
            "binary_name":  "mail-stack-delivery",
            "binary_version":  "1:2.2.9-1ubuntu2.6+esm4"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40017.json"