Bug 2452179 (CVE-2026-27857) - CVE-2026-27857 dovecot: denial of service via specially crafted NOOP command
Summary: CVE-2026-27857 dovecot: denial of service via specially crafted NOOP command
Keywords:
Status: NEW
Alias: CVE-2026-27857
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On: 2452244 2452246 2452245
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-03-27 09:02 UTC by OSIDB Bzimport
Modified: 2026-05-14 15:25 UTC (History)
0 users

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2026:13498 0 None None None 2026-05-04 13:48:47 UTC
Red Hat Product Errata RHSA-2026:13830 0 None None None 2026-05-05 17:11:53 UTC
Red Hat Product Errata RHSA-2026:13857 0 None None None 2026-05-05 19:18:28 UTC
Red Hat Product Errata RHSA-2026:17602 0 None None None 2026-05-14 14:00:47 UTC
Red Hat Product Errata RHSA-2026:17625 0 None None None 2026-05-14 15:10:21 UTC
Red Hat Product Errata RHSA-2026:17626 0 None None None 2026-05-14 15:25:00 UTC
Red Hat Product Errata RHSA-2026:17628 0 None None None 2026-05-14 15:14:07 UTC
Red Hat Product Errata RHSA-2026:17630 0 None None None 2026-05-14 15:02:30 UTC

Description OSIDB Bzimport 2026-03-27 09:02:22 UTC 
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.
Comment 2 errata-xmlrpc 2026-05-04 13:48:46 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:13498 https://access.redhat.com/errata/RHSA-2026:13498
Comment 3 errata-xmlrpc 2026-05-05 17:11:52 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:13830 https://access.redhat.com/errata/RHSA-2026:13830
Comment 4 errata-xmlrpc 2026-05-05 19:18:27 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:13857 https://access.redhat.com/errata/RHSA-2026:13857
Comment 5 errata-xmlrpc 2026-05-14 14:00:46 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10.0 Extended Update Support

Via RHSA-2026:17602 https://access.redhat.com/errata/RHSA-2026:17602
Comment 6 errata-xmlrpc 2026-05-14 15:02:29 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions

Via RHSA-2026:17630 https://access.redhat.com/errata/RHSA-2026:17630
Comment 7 errata-xmlrpc 2026-05-14 15:10:20 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Extended Update Support

Via RHSA-2026:17625 https://access.redhat.com/errata/RHSA-2026:17625
Comment 8 errata-xmlrpc 2026-05-14 15:14:06 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:17628 https://access.redhat.com/errata/RHSA-2026:17628
Comment 9 errata-xmlrpc 2026-05-14 15:24:59 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:17626 https://access.redhat.com/errata/RHSA-2026:17626
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