UBUNTU-CVE-2026-40203

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Source
https://ubuntu.com/security/CVE-2026-40203
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40203.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-40203
Upstream
  • CVE-2026-40203
Published
2026-08-28T00:00:00Z
Modified
2026-09-02T19:36:04Z
Severity
  • 3.7 (Low) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

When IMAP compression is enabled, the same compression state is reused across responses in a session, so response sizes depend on both attacker-supplied mail and other mail in the same mailbox. An attacker that can send mail to a user and can also observe the sizes of that user's IMAP traffic can confirm whether the body of a small message matches a guessed text. Recovery of arbitrary unknown content was not demonstrated, but the attack can disclose whether a secret-like message body matches a candidate. Disable IMAP compression. 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-2026-40203.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-2026-40203.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-2026-40203.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-2026-40203.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-2026-40203.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-2026-40203.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-2026-40203.json"