Detections
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Amazon Linux 2 : dovecot, --advisory ALAS2-2026-3252 (ALAS-2026-3252)
medium Nessus Plugin ID 311199
Synopsis
The remote Amazon Linux 2 host is missing a security update.Description
The version of dovecot installed on the remote host is prior to 2.2.36-6. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2026-3252 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)
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 'yum update dovecot' or or 'yum update --advisory ALAS2-2026-3252' to update your system.See Also
https://alas.aws.amazon.com//AL2/ALAS2-2026-3252.html
https://alas.aws.amazon.com/faqs.html
Plugin Details
Severity: Medium
ID: 311199
File Name: al2_ALAS-2026-3252.nasl
Version: 1.1
Type: Local
Agent: unix
Published: 4/30/2026
Updated: 4/30/2026
Supported Sensors: Nessus Agent, Continuous Assessment, Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 4.4
CVSS v2
Risk Factor: Medium
Base Score: 5.4
Temporal Score: 4
Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:N/A:N
CVSS Score Source: CVE-2026-27856
CVSS v3
Risk Factor: Medium
Base Score: 5.9
Temporal Score: 5.2
Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
Vulnerability Information
CPE: p-cpe:/a:amazon:linux:dovecot-debuginfo, p-cpe:/a:amazon:linux:dovecot-pigeonhole, cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:dovecot, p-cpe:/a:amazon:linux:dovecot-devel, p-cpe:/a:amazon:linux:dovecot-pgsql, p-cpe:/a:amazon:linux:dovecot-mysql
Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list
Exploit Ease: No known exploits are available
Patch Publication Date: 4/30/2026
Vulnerability Publication Date: 3/27/2026
Reference Information
CVE: CVE-2026-27856, CVE-2026-27857