Detections
Analytics
Amazon Linux 2023 : dovecot, dovecot-devel, dovecot-mysql (ALAS2023-2026-1570)
high Nessus Plugin ID 306220
Synopsis
The remote Amazon Linux 2023 host is missing a security update.Description
It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1570 advisory.Doveadm credentials are verified using direct comparison which is susceptible to timing oracle attack. An attacker can use this to determine the configured credentials. Figuring out the credential will lead into full access to the affected component. Limit access to the doveadm http service port, install fixed version. No publicly available exploits are known. (CVE-2026-27856)
Sending NOOP (((...))) command with 4000 parenthesis open+close results in ~1MB extra memory usage.
Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time periods by not sending the command ending LF. So attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Install fixed version, there is no other remediation. No publicly available exploits are known. (CVE-2026-27857)
Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory.Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access to managesieve protocol, or install fixed version. No publicly available exploits are known. (CVE-2026-27858)
Tenable has extracted the preceding description block directly from the tested product security advisory.
Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.
Solution
Run 'dnf update dovecot --releasever 2023.11.20260413' or or 'dnf update --advisory ALAS2023-2026-1570 --releasever 2023.11.20260413' to update your system.See Also
https://alas.aws.amazon.com//AL2023/ALAS2023-2026-1570.html
https://alas.aws.amazon.com/faqs.html
https://explore.alas.aws.amazon.com/CVE-2026-27856.html
Plugin Details
Severity: High
ID: 306220
File Name: al2023_ALAS2023-2026-1570.nasl
Version: 1.1
Type: Local
Agent: unix
Published: 4/13/2026
Updated: 4/13/2026
Supported Sensors: Agentless Assessment, Continuous Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Nessus Agent, Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 6.0
CVSS v2
Risk Factor: High
Base Score: 7.1
Temporal Score: 5.3
Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:N
CVSS Score Source: CVE-2026-27856
CVSS v3
Risk Factor: High
Base Score: 7.4
Temporal Score: 6.4
Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
Vulnerability Information
CPE: p-cpe:/a:amazon:linux:dovecot-mysql-debuginfo, p-cpe:/a:amazon:linux:dovecot, p-cpe:/a:amazon:linux:dovecot-debugsource, p-cpe:/a:amazon:linux:dovecot-pigeonhole-debuginfo, p-cpe:/a:amazon:linux:dovecot-pgsql-debuginfo, p-cpe:/a:amazon:linux:dovecot-pigeonhole, p-cpe:/a:amazon:linux:dovecot-devel, p-cpe:/a:amazon:linux:dovecot-debuginfo, p-cpe:/a:amazon:linux:dovecot-pgsql, p-cpe:/a:amazon:linux:dovecot-mysql, cpe:/o:amazon:linux:2023
Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list
Exploit Ease: No known exploits are available
Patch Publication Date: 4/13/2026
Vulnerability Publication Date: 3/27/2026