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High 7.5Published Mar 27, 2026

CVE-2026-27857Sending "NOOP (((...)))" command with 4000 parenthesis open+close results in ~1MB extra memory usage.

Updated under an hour ago ()

Does this affect you?

It affects dovecot and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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.

CVSS
7.5 HIGH (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE)
CWE-400, CWE-770
Known exploited
Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days)
Not loaded for this CVE
Assigned by
Not given
NVD analysis
Modified
Record last updated
Jul 15, 2026
First seen by InfoSec Signals
Oct 9, 2026

Affected products

Affected products
dovecot dovecot
dovecot:dovecot
before 2.4.3
NVD
open-xchange dovecot
open-xchange:dovecot
before 2.3.22.1; from 3.0.0 before 3.0.5; from 3.1.0 before 3.1.4
NVD

References

  • vendor-advisory

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.

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