Detections
Analytics
CVE-2026-27857
high
Description
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.
References
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27857.json
https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json
https://bugzilla.redhat.com/show_bug.cgi?id=2452179
https://access.redhat.com/security/cve/CVE-2026-27857
https://access.redhat.com/errata/RHSA-2026:26564
https://access.redhat.com/errata/RHSA-2026:19455
https://access.redhat.com/errata/RHSA-2026:19453
https://access.redhat.com/errata/RHSA-2026:19364
https://access.redhat.com/errata/RHSA-2026:19149
https://access.redhat.com/errata/RHSA-2026:18053
https://access.redhat.com/errata/RHSA-2026:17630
https://access.redhat.com/errata/RHSA-2026:17628
https://access.redhat.com/errata/RHSA-2026:17626
https://access.redhat.com/errata/RHSA-2026:17625
https://access.redhat.com/errata/RHSA-2026:17602
https://access.redhat.com/errata/RHSA-2026:13857