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 2452245 2452246
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-03-27 09:02 UTC by OSIDB Bzimport
Modified: 2026-03-27 14:39 UTC (History)
0 users

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


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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.


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