USN-8365-1: Dovecot vulnerabilities

It was discovered that Dovecot incorrectly treated some variable expansion
pipelines as safe in authentication filters. An attacker could possibly use
this issue to perform SQL or LDAP injection attacks. This issue only
affected Ubuntu 25.10 and Ubuntu 26.04 LTS. (CVE-2026-27851)

It was discovered that Dovecot incorrectly verified SCRAM TLS channel
binding in certain base64 exchanges. A remote attacker could possibly use
this issue to obtain sensitive information in a machine-in-the-middle
attack. (CVE-2026-33603)

It was discovered that Dovecot incorrectly enforced Sieve script CPU
limits. An attacker could possibly use this issue to cause Dovecot to use
excessive resources, leading to a denial of service. (CVE-2026-40016)

It was discovered that Dovecot incorrectly handled certain IMAP SETACL
commands. An attacker could possibly use this issue to spam folders to
other users. (CVE-2026-40020)

It was discovered that Dovecot incorrectly handled excessive IMAP bracing.
An attacker could possibly use this issue to cause Dovecot to use excessive
resources, leading to a denial of service. (CVE-2026-42006)

SecRule REQUEST_URI "@rx ..." "id:1001,phase:1,deny,status:403"

find /var/www -type f -name "*.php" -mmin -120

ss -tunp | grep -E ":(4444|1337|8080|9001)"

apt update && apt --only-upgrade install <pkg>

title: Detect Exploitation - USN-8365-1: Dovecot vulnerabilities
id: 54e2cc54-f9cd-42ab-81b8-370c2b0bb8c9
status: experimental
description: Automatisch generierte SIEM-Erkennungsregel basierend auf CTI Intelligence
references:
  - https://tsecurity.de/
author: iShareStuff CTI Automated Detection Engine
date: 2026-09-24
logsource:
  category: network_connection
  product: any
detection:
  selection:
      CommandLine|contains:
        - 'exploit'
  condition: selection
falsepositives:
  - Legitime administrative Zugriffe oder Penetrationstests
level: high
tags:
  - attack.initial_access

rule CTI_Threat_Indicator {
    meta:
        author = "iShareStuff CTI Automated Detection Engine"
        date = "2026-09-24"
        description = "YARA Signature for "
    strings:
        $str = "USN-8365-1: Dovecot vulnerabil" ascii wide
    condition:
        any of them
}