CVE-2026-27857

Name
CVE-2026-27857
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.
NVD Severity
unknown
Other trackers
CVE, NVD, CERT, CVE Details, CIRCL, Arch Linux, Debian, Red Hat, Ubuntu, Gentoo, SUSE (Bugzilla), SUSE (CVE), Mageia
Mailing lists
oss-security, full-disclosure, bugtraq
Exploits
Exploit DB, Metasploit
Forges
GitHub (code, issues), Aports (code, issues)

References

Type URI
security@open-xchange.com https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/errata/RHSA-2026:13498
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/errata/RHSA-2026:13830
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/errata/RHSA-2026:13857
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/errata/RHSA-2026:17602
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/errata/RHSA-2026:17625
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/errata/RHSA-2026:17626
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/errata/RHSA-2026:17628
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/errata/RHSA-2026:17630
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/errata/RHSA-2026:18053
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/errata/RHSA-2026:19149
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/errata/RHSA-2026:19364
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/errata/RHSA-2026:19453
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/errata/RHSA-2026:19455
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/errata/RHSA-2026:26564
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://access.redhat.com/security/cve/CVE-2026-27857
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://bugzilla.redhat.com/show_bug.cgi?id=2452179
0b0ca135-0b70-47e7-9f44-1890c2a1c46c https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27857.json

Match rules

CPE URI Source package Min version Max version
cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:* dovecot >= None < 2.4.3
cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:* dovecot >= None < 2.3.22.1
cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:* dovecot >= 3.0.0 < 3.0.5
cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:* dovecot >= 3.1.0 < 3.1.4

Vulnerable and fixed packages

Source package Branch Version Maintainer Status
dovecot edge-main 2.4.3-r0 Natanael Copa <ncopa@alpinelinux.org> fixed
dovecot edge-main 2.4.2-r2 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot edge-main 2.4.2-r1 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot edge-main 2.4.2-r0 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot edge-main 2.4.1-r3 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot edge-main 2.4.1-r2 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot edge-main 2.4.1-r1 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot edge-main 2.4.1-r0 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot edge-main 2.4.0-r1 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot edge-main 2.4.0-r0 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot edge-main 2.3.21.1-r0 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot edge-main 2.3.19.1-r6 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot edge-main 2.3.19.1-r5 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot edge-main 2.3.15-r0 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot edge-main 2.3.13-r0 None possibly vulnerable
dovecot edge-main 2.3.11.3-r0 None possibly vulnerable
dovecot edge-main 2.3.10.1-r0 None possibly vulnerable
dovecot edge-main 2.3.9.3-r0 None possibly vulnerable
dovecot edge-main 2.3.9.2-r0 None possibly vulnerable
dovecot edge-main 2.3.7.2-r0 None possibly vulnerable
dovecot edge-main 2.3.6-r0 None possibly vulnerable
dovecot edge-main 2.3.5.1-r0 None possibly vulnerable
dovecot edge-main 2.3.4.1-r0 None possibly vulnerable
dovecot edge-main 2.3.1-r0 None possibly vulnerable
dovecot 3.23-main 2.4.3-r0 Natanael Copa <ncopa@alpinelinux.org> fixed
dovecot 3.23-main 2.4.2-r1 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot 3.22-main 2.4.1-r2 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot 3.22-main 2.3.21.1-r0 None possibly vulnerable
dovecot 3.22-main 2.3.19.1-r5 None possibly vulnerable
dovecot 3.22-main 2.3.15-r0 None possibly vulnerable
dovecot 3.22-main 2.3.13-r0 None possibly vulnerable
dovecot 3.22-main 2.3.11.3-r0 None possibly vulnerable
dovecot 3.22-main 2.3.10.1-r0 None possibly vulnerable
dovecot 3.22-main 2.3.9.3-r0 None possibly vulnerable
dovecot 3.22-main 2.3.9.2-r0 None possibly vulnerable
dovecot 3.22-main 2.3.7.2-r0 None possibly vulnerable
dovecot 3.22-main 2.3.6-r0 None possibly vulnerable
dovecot 3.22-main 2.3.5.1-r0 None possibly vulnerable
dovecot 3.22-main 2.3.4.1-r0 None possibly vulnerable
dovecot 3.22-main 2.3.1-r0 None possibly vulnerable
dovecot 3.21-main 2.3.21.1-r0 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot 3.21-main 2.3.19.1-r5 None possibly vulnerable
dovecot 3.21-main 2.3.15-r0 None possibly vulnerable
dovecot 3.21-main 2.3.13-r0 None possibly vulnerable
dovecot 3.21-main 2.3.11.3-r0 None possibly vulnerable
dovecot 3.21-main 2.3.10.1-r0 None possibly vulnerable
dovecot 3.21-main 2.3.9.3-r0 None possibly vulnerable
dovecot 3.21-main 2.3.9.2-r0 None possibly vulnerable
dovecot 3.21-main 2.3.7.2-r0 None possibly vulnerable
dovecot 3.21-main 2.3.6-r0 None possibly vulnerable
dovecot 3.21-main 2.3.5.1-r0 None possibly vulnerable
dovecot 3.21-main 2.3.4.1-r0 None possibly vulnerable
dovecot 3.21-main 2.3.1-r0 None possibly vulnerable
dovecot 3.20-main 2.3.21.1-r0 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot 3.20-main 2.3.19.1-r5 None possibly vulnerable
dovecot 3.20-main 2.3.15-r0 None possibly vulnerable
dovecot 3.20-main 2.3.13-r0 None possibly vulnerable
dovecot 3.20-main 2.3.11.3-r0 None possibly vulnerable
dovecot 3.20-main 2.3.10.1-r0 None possibly vulnerable
dovecot 3.20-main 2.3.9.3-r0 None possibly vulnerable
dovecot 3.20-main 2.3.9.2-r0 None possibly vulnerable
dovecot 3.20-main 2.3.7.2-r0 None possibly vulnerable
dovecot 3.20-main 2.3.6-r0 None possibly vulnerable
dovecot 3.20-main 2.3.5.1-r0 None possibly vulnerable
dovecot 3.20-main 2.3.4.1-r0 None possibly vulnerable
dovecot 3.20-main 2.3.1-r0 None possibly vulnerable
dovecot 3.19-main 2.3.21-r17 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
dovecot 3.19-main 2.3.19.1-r5 None possibly vulnerable
dovecot 3.19-main 2.3.15-r0 None possibly vulnerable
dovecot 3.19-main 2.3.13-r0 None possibly vulnerable
dovecot 3.19-main 2.3.11.3-r0 None possibly vulnerable
dovecot 3.19-main 2.3.10.1-r0 None possibly vulnerable
dovecot 3.19-main 2.3.9.3-r0 None possibly vulnerable
dovecot 3.19-main 2.3.9.2-r0 None possibly vulnerable
dovecot 3.19-main 2.3.7.2-r0 None possibly vulnerable
dovecot 3.19-main 2.3.6-r0 None possibly vulnerable
dovecot 3.19-main 2.3.5.1-r0 None possibly vulnerable
dovecot 3.19-main 2.3.4.1-r0 None possibly vulnerable
dovecot 3.19-main 2.3.1-r0 None possibly vulnerable