CVE-2026-27857

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.

The following products are affected by CVE-2026-27857 vulnerability.

Here, you will find a curated list of external links that provide in-depth information to CVE-2026-27857.

URL	Resource
https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json
https://nvd.nist.gov/vuln/detail/CVE-2026-27857
https://www.cve.org/CVERecord?id=CVE-2026-27857