CVE-2026-27857
Описание уязвимости
Что произошло
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.
Что это значит
В источнике описана ошибка безопасности в перечисленных продуктах. Фактический риск зависит от установленной версии, конфигурации и доступности компонента; проверьте условия в первичном бюллетене.
Что делать
1. Проверьте, затронуты ли вы
Соберите инвентаризацию и сравните с таблицей затронутых версий. Эти команды только показывают установленные компоненты и сами по себе не доказывают наличие CVE.
dpkg-query -W -f='${Package} ${Version}\n'rpm -qa --qf '%{NAME}\t%{VERSION}-%{RELEASE}\n'Get-HotFix | Select-Object HotFixID, InstalledOn
2. Установите исправление
RHSA-2026:26564: Red Hat Enterprise Linux Server (v. 7 ELS), Red Hat Enterprise Linux Server Optional (v. 7 ELS)
RHSA-2026:17602: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)
RHSA-2026:13498: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)
RHSA-2026:19149: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)
RHSA-2026:13830: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux CRB (v. 8)
RHSA-2026:19455: Red Hat Enterprise Linux AppStream AUS (v.8.4), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)
RHSA-2026:19453: Red Hat Enterprise Linux AppStream AUS (v.8.6), Red Hat Enterprise Linux AppStream E4S (v.8.6), Red Hat Enterprise Linux AppStream TUS (v.8.6)
RHSA-2026:18053: Red Hat Enterprise Linux AppStream E4S (v.8.8), Red Hat Enterprise Linux AppStream TUS (v.8.8)
RHSA-2026:17630: Red Hat Enterprise Linux AppStream E4S (v.9.0)
RHSA-2026:17628: Red Hat Enterprise Linux AppStream E4S (v.9.2)
RHSA-2026:17625: Red Hat CodeReady Linux Builder EUS (v.9.4), Red Hat Enterprise Linux AppStream EUS (v.9.4)
RHSA-2026:17626: Red Hat CodeReady Linux Builder EUS (v.9.6), Red Hat Enterprise Linux AppStream EUS (v.9.6)
RHSA-2026:13857: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)
RHSA-2026:19364: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)
3. Временные меры
Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.
4. Проверьте следы эксплуатации
Проверьте аномальные входы, новые учётные записи, ошибки и необычные дочерние процессы в затронутом сервисе. Публичные проверенные правила обнаружения не включены в запись; отсутствие сигналов не доказывает отсутствие компрометации.
5. После исправления
- Проверьте фактическую версию и результат установки по бюллетеню.
- При необходимости перезапустите сервисы в согласованное окно.
- Повторите проверку сканером и функциональные проверки.
- Зафиксируйте результат, дату, владельца и оставшийся риск.
Продукты и затронутые версии
Open-Xchange GmbH / OX Dovecot Pro
{
"status": "affected",
"version": "0",
"versionType": "semver",
"lessThanOrEqual": "2.3.0"
}Red Hat / Red Hat Enterprise Linux 10
{
"status": "unaffected",
"version": "1:2.3.21-16.el10_1.1",
"lessThan": "*",
"versionType": "rpm"
}{
"status": "unaffected",
"version": "1:2.3.21-19.el10_2",
"lessThan": "*",
"versionType": "rpm"
}cpe:/o:redhat:enterprise_linux:10.1
cpe:/o:redhat:enterprise_linux:10.2
Red Hat / Red Hat Enterprise Linux 10.0 Extended Update Support
{
"status": "unaffected",
"version": "1:2.3.21-16.el10_0.1",
"lessThan": "*",
"versionType": "rpm"
}cpe:/o:redhat:enterprise_linux_eus:10.0
Red Hat / Red Hat Enterprise Linux 7 Extended Lifecycle Support
{
"status": "unaffected",
"version": "1:2.2.36-8.el7_9.1",
"lessThan": "*",
"versionType": "rpm"
}cpe:/o:redhat:rhel_els:7
Red Hat / Red Hat Enterprise Linux 8
{
"status": "unaffected",
"version": "1:2.3.16-7.el8_10",
"lessThan": "*",
"versionType": "rpm"
}cpe:/a:redhat:enterprise_linux:8
Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
{
"status": "unaffected",
"version": "1:2.3.8-9.el8_4.1",
"lessThan": "*",
"versionType": "rpm"
}cpe:/a:redhat:rhel_aus:8.4
Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
{
"status": "unaffected",
"version": "1:2.3.8-9.el8_4.1",
"lessThan": "*",
"versionType": "rpm"
}cpe:/a:redhat:rhel_eus_long_life:8.4
Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
{
"status": "unaffected",
"version": "1:2.3.16-2.el8_6.1",
"lessThan": "*",
"versionType": "rpm"
}cpe:/a:redhat:rhel_aus:8.6
Red Hat / Red Hat Enterprise Linux 8.6 Telecommunications Update Service
{
"status": "unaffected",
"version": "1:2.3.16-2.el8_6.1",
"lessThan": "*",
"versionType": "rpm"
}cpe:/a:redhat:rhel_tus:8.6
Red Hat / Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions
{
"status": "unaffected",
"version": "1:2.3.16-2.el8_6.1",
"lessThan": "*",
"versionType": "rpm"
}cpe:/a:redhat:rhel_e4s:8.6
Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Service
{
"status": "unaffected",
"version": "1:2.3.16-3.el8_8.1",
"lessThan": "*",
"versionType": "rpm"
}cpe:/a:redhat:rhel_tus:8.8
Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
{
"status": "unaffected",
"version": "1:2.3.16-3.el8_8.1",
"lessThan": "*",
"versionType": "rpm"
}cpe:/a:redhat:rhel_e4s:8.8
Red Hat / Red Hat Enterprise Linux 9
{
"status": "unaffected",
"version": "1:2.3.16-15.el9_7.1",
"lessThan": "*",
"versionType": "rpm"
}{
"status": "unaffected",
"version": "1:2.3.16-18.el9_8",
"lessThan": "*",
"versionType": "rpm"
}cpe:/a:redhat:enterprise_linux:9
Red Hat / Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions
{
"status": "unaffected",
"version": "1:2.3.16-3.el9_0.1",
"lessThan": "*",
"versionType": "rpm"
}cpe:/a:redhat:rhel_e4s:9.0
Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
{
"status": "unaffected",
"version": "1:2.3.16-8.el9_2.2",
"lessThan": "*",
"versionType": "rpm"
}cpe:/a:redhat:rhel_e4s:9.2
Red Hat / Red Hat Enterprise Linux 9.4 Extended Update Support
{
"status": "unaffected",
"version": "1:2.3.16-11.el9_4.2",
"lessThan": "*",
"versionType": "rpm"
}cpe:/a:redhat:rhel_eus:9.4
Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Support
{
"status": "unaffected",
"version": "1:2.3.16-15.el9_6.1",
"lessThan": "*",
"versionType": "rpm"
}cpe:/a:redhat:rhel_eus:9.6
Red Hat / Red Hat Enterprise Linux 6
cpe:/o:redhat:enterprise_linux:6
dovecot / dovecot
{
"status": "affected",
"version": "*",
"versionEndExcluding": "2.4.3"
}cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:*
open-xchange / dovecot
{
"status": "affected",
"version": "*",
"versionEndExcluding": "2.3.22.1"
}cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*
open-xchange / dovecot
{
"status": "affected",
"version": "*",
"versionEndExcluding": "3.0.5",
"versionStartIncluding": "3.0.0"
}cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*
open-xchange / dovecot
{
"status": "affected",
"version": "*",
"versionEndExcluding": "3.1.4",
"versionStartIncluding": "3.1.0"
}cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*
CVSS: оценки и векторы
CVSS 3.1 · cve4.3
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
CVSS 3.1 · cve7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.1 · security@open-xchange.com4.3
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
CVSS 3.1 · nvd@nist.gov7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.1 · 0b0ca135-0b70-47e7-9f44-1890c2a1c46c7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Источники и ссылки
Происхождение полей
{
"cwes": [
"cve",
"nvd"
],
"epss": {
"source": "epss",
"received_at": "2026-11-02T21:12:05.283194+00:00"
},
"scores": [
"cve",
"nvd"
],
"status": {
"source": "cve",
"received_at": "2026-10-28T19:27:00.423764+00:00"
},
"affected": [
"cve",
"nvd"
],
"published": {
"source": "cve",
"received_at": "2026-10-28T19:27:00.423764+00:00"
},
"solutions": [
"cve"
],
"percentile": {
"source": "epss",
"received_at": "2026-11-02T21:12:05.283194+00:00"
},
"references": [
"cve",
"nvd"
],
"description": {
"source": "cve",
"received_at": "2026-10-28T19:27:00.423764+00:00"
},
"workarounds": [
"cve"
],
"configurations": [
"nvd"
]
}Хронология записи
- Данные обновлены03.11.2026, 00:12
- Данные обновлены02.11.2026, 00:10
- Данные обновлены31.10.2026, 11:57
- Данные обновлены28.10.2026, 22:27
- Данные обновлены28.10.2026, 18:06
- Опубликована28.10.2026, 15:11
Личная заметка и статус
Другие CVE того же продукта
| УЯЗВИМОСТЬ / ПРОДУКТ | ПРИОРИТЕТ | CVSS | EPSS | СИГНАЛЫ | ОПУБЛИКОВАНА | Карточка |
|---|---|---|---|---|---|---|
| CVE-2026-27855 Dovecot OTP authentication is vulnerable to replay attack under specific conditions. If auth cache i Open-Xchange GmbH / OX Dovecot Pro · dovecot / dovecot | Средний | 6.8 | 0,32 % | 27.03.2026 | ||
| CVE-2026-27856 Doveadm credentials are verified using direct comparison which is susceptible to timing oracle attac Open-Xchange GmbH / OX Dovecot Pro · Red Hat / Red Hat Enterprise Linux 7 Extended Lifecycle Support | Высокий | 7.4 | 0,4 % | 27.03.2026 | ||
| CVE-2026-27858 Attacker can send a specifically crafted message before authentication that causes managesieve to al Open-Xchange GmbH / OX Dovecot Pro · Red Hat / Red Hat Enterprise Linux 10 | Высокий | 7.5 | 0,8 % | 27.03.2026 | ||
| CVE-2026-24031 Dovecot SQL based authentication can be bypassed when auth_username_chars is cleared by admin. This Open-Xchange GmbH / OX Dovecot Pro · Red Hat / Red Hat Enterprise Linux 10 | Высокий | 8.2 | 0,4 % | 27.03.2026 | ||
| CVE-2026-0394 When dovecot has been configured to use per-domain passwd files, and they are placed one path compon Open-Xchange GmbH / OX Dovecot Pro · dovecot / dovecot | Средний | 5.3 | 0,44 % | 27.03.2026 |