CVE-2026-27857Sending "NOOP (((...)))" command with 4000 parenthesis open+close results in ~1MB extra memory usage.
Updated under an hour ago ()
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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.
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Free account, 1 product
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
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
- https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.jsonvendor-advisory
- https://access.redhat.com/errata/RHSA-2026:13498
- https://access.redhat.com/errata/RHSA-2026:13830
- https://access.redhat.com/errata/RHSA-2026:13857
- https://access.redhat.com/errata/RHSA-2026:17602
- https://access.redhat.com/errata/RHSA-2026:17625
- https://access.redhat.com/errata/RHSA-2026:17626
- https://access.redhat.com/errata/RHSA-2026:17628
- https://access.redhat.com/errata/RHSA-2026:17630
- https://access.redhat.com/errata/RHSA-2026:18053
- https://access.redhat.com/errata/RHSA-2026:19149
- https://access.redhat.com/errata/RHSA-2026:19364
- https://access.redhat.com/errata/RHSA-2026:19453
- https://access.redhat.com/errata/RHSA-2026:19455
- https://access.redhat.com/errata/RHSA-2026:26564
- https://access.redhat.com/security/cve/CVE-2026-27857
- https://bugzilla.redhat.com/show_bug.cgi?id=2452179
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27857.json
The CVE record on cve.org NVD's entry
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.