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TI-2026-22207 Aliases CVE-2026-27857GHSA-j26c-8p6m-gpfj

Uncontrolled resource consumption in Open-Xchange GmbH OX Dovecot Pro

Priority LOW 34CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 23 fixed, 1 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-400.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00679 52nd percentileScored 2026-11-07
Fix Partial Red Hat: 14 advisoriesRed Hat: 23 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
Open-Xchange GmbHOX Dovecot Proup to 2.3.0—No fix listedCNA
  • OX Dovecot Pro VendorOpen-Xchange GmbH Affected up to 2.3.0 Fixed in — No fix listed CNA

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:*before 2.4.3VulnerableThe Dovecot Project
cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*before 2.3.22.1; 3.0.0 to before 3.0.5; 3.1.0 to before 3.1.4VulnerableOpen-Xchange GmbH
  • cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:* Versions before 2.4.3 Vulnerable ·The Dovecot Project
  • cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:* Versions before 2.3.22.1; 3.0.0 to before 3.0.5; 3.1.0 to before 3.1.4 Vulnerable ·Open-Xchange GmbH

Remediation

Red Hat 14 advisories

  • RHSA-2026:26564 Released 2026-06-17 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux Server (v. 7 ELS) dovecot-1:2.2.36-8.el7_9.1, dovecot-1:2.2.36-8.el7_9.1.ppc, dovecot-mysql-1:2.2.36-8.el7_9.1 +2
    • Red Hat Enterprise Linux Server Optional (v. 7 ELS) dovecot-devel-1:2.2.36-8.el7_9.1
  • RHSA-2026:19455 Released 2026-05-20 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream AUS (v.8.4) dovecot-1:2.3.8-9.el8_4.1, dovecot-mysql-1:2.3.8-9.el8_4.1, dovecot-pgsql-1:2.3.8-9.el8_4.1 +1
    • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) dovecot-1:2.3.8-9.el8_4.1, dovecot-mysql-1:2.3.8-9.el8_4.1, dovecot-pgsql-1:2.3.8-9.el8_4.1 +1
  • RHSA-2026:19453 Released 2026-05-20 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream AUS (v.8.6) dovecot-1:2.3.16-2.el8_6.1, dovecot-mysql-1:2.3.16-2.el8_6.1, dovecot-pgsql-1:2.3.16-2.el8_6.1 +1
    • Red Hat Enterprise Linux AppStream E4S (v.8.6) dovecot-1:2.3.16-2.el8_6.1, dovecot-mysql-1:2.3.16-2.el8_6.1, dovecot-pgsql-1:2.3.16-2.el8_6.1 +1
    • Red Hat Enterprise Linux AppStream TUS (v.8.6) dovecot-1:2.3.16-2.el8_6.1, dovecot-mysql-1:2.3.16-2.el8_6.1, dovecot-pgsql-1:2.3.16-2.el8_6.1 +1
Show 11 more Red Hat advisories
  • RHSA-2026:19364 Released 2026-05-19 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream (v. 9) dovecot-1:2.3.16-18.el9_8, dovecot-mysql-1:2.3.16-18.el9_8, dovecot-pgsql-1:2.3.16-18.el9_8 +1
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) dovecot-1:2.3.16-18.el9_8, dovecot-devel-1:2.3.16-18.el9_8
  • RHSA-2026:19149 Released 2026-05-19 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream (v. 10) dovecot-1:2.3.21-19.el10_2, dovecot-mysql-1:2.3.21-19.el10_2, dovecot-pgsql-1:2.3.21-19.el10_2 +1
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) dovecot-devel-1:2.3.21-19.el10_2
  • RHSA-2026:18053 Released 2026-05-18 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream E4S (v.8.8) dovecot-1:2.3.16-3.el8_8.1, dovecot-mysql-1:2.3.16-3.el8_8.1, dovecot-pgsql-1:2.3.16-3.el8_8.1 +1
    • Red Hat Enterprise Linux AppStream TUS (v.8.8) dovecot-1:2.3.16-3.el8_8.1, dovecot-mysql-1:2.3.16-3.el8_8.1, dovecot-pgsql-1:2.3.16-3.el8_8.1 +1
  • RHSA-2026:17626 Released 2026-05-14 · Red Hat rating Important
    dovecot security update
    • Red Hat CodeReady Linux Builder EUS (v.9.6) dovecot-1:2.3.16-15.el9_6.1, dovecot-devel-1:2.3.16-15.el9_6.1
    • Red Hat Enterprise Linux AppStream EUS (v.9.6) dovecot-1:2.3.16-15.el9_6.1, dovecot-mysql-1:2.3.16-15.el9_6.1, dovecot-pgsql-1:2.3.16-15.el9_6.1 +1
  • RHSA-2026:17628 Released 2026-05-14 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream E4S (v.9.2) dovecot-1:2.3.16-8.el9_2.2, dovecot-mysql-1:2.3.16-8.el9_2.2, dovecot-pgsql-1:2.3.16-8.el9_2.2 +1
  • RHSA-2026:17625 Released 2026-05-14 · Red Hat rating Important
    dovecot security update
    • Red Hat CodeReady Linux Builder EUS (v.9.4) dovecot-1:2.3.16-11.el9_4.2, dovecot-devel-1:2.3.16-11.el9_4.2
    • Red Hat Enterprise Linux AppStream EUS (v.9.4) dovecot-1:2.3.16-11.el9_4.2, dovecot-mysql-1:2.3.16-11.el9_4.2, dovecot-pgsql-1:2.3.16-11.el9_4.2 +1
  • RHSA-2026:17630 Released 2026-05-14 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream E4S (v.9.0) dovecot-1:2.3.16-3.el9_0.1, dovecot-mysql-1:2.3.16-3.el9_0.1, dovecot-pgsql-1:2.3.16-3.el9_0.1 +1
  • RHSA-2026:17602 Released 2026-05-14 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream EUS (v. 10.0) dovecot-1:2.3.21-16.el10_0.1, dovecot-mysql-1:2.3.21-16.el10_0.1, dovecot-pgsql-1:2.3.21-16.el10_0.1 +1
    • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) dovecot-devel-1:2.3.21-16.el10_0.1
  • RHSA-2026:13857 Released 2026-05-05 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream (v. 9) dovecot-1:2.3.16-15.el9_7.1, dovecot-mysql-1:2.3.16-15.el9_7.1, dovecot-pgsql-1:2.3.16-15.el9_7.1 +1
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) dovecot-1:2.3.16-15.el9_7.1, dovecot-devel-1:2.3.16-15.el9_7.1
  • RHSA-2026:13830 Released 2026-05-05 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream (v. 8) dovecot-1:2.3.16-7.el8_10, dovecot-mysql-1:2.3.16-7.el8_10, dovecot-pgsql-1:2.3.16-7.el8_10 +1
    • Red Hat Enterprise Linux CRB (v. 8) dovecot-1:2.3.16-7.el8_10, dovecot-devel-1:2.3.16-7.el8_10
  • RHSA-2026:13498 Released 2026-05-04 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream (v. 10) dovecot-1:2.3.21-16.el10_1.1, dovecot-mysql-1:2.3.21-16.el10_1.1, dovecot-pgsql-1:2.3.21-16.el10_1.1 +1
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) dovecot-devel-1:2.3.21-16.el10_1.1

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Will not fix
Red Hat CodeReady Linux Builder EUS (v.9.4)Fixed RHSA-2026:17625
Red Hat CodeReady Linux Builder EUS (v.9.6)Fixed RHSA-2026:17626
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:13498, RHSA-2026:19149
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2026:13830
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2026:13857, RHSA-2026:19364
Red Hat Enterprise Linux AppStream AUS (v.8.4)Fixed RHSA-2026:19455
Red Hat Enterprise Linux AppStream AUS (v.8.6)Fixed RHSA-2026:19453
Red Hat Enterprise Linux AppStream E4S (v.8.6)Fixed RHSA-2026:19453
Red Hat Enterprise Linux AppStream E4S (v.8.8)Fixed RHSA-2026:18053
Red Hat Enterprise Linux AppStream E4S (v.9.0)Fixed RHSA-2026:17630
Red Hat Enterprise Linux AppStream E4S (v.9.2)Fixed RHSA-2026:17628
Red Hat Enterprise Linux AppStream EUS (v. 10.0)Fixed RHSA-2026:17602
Red Hat Enterprise Linux AppStream EUS (v.9.4)Fixed RHSA-2026:17625
Red Hat Enterprise Linux AppStream EUS (v.9.6)Fixed RHSA-2026:17626
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)Fixed RHSA-2026:19455
Red Hat Enterprise Linux AppStream TUS (v.8.6)Fixed RHSA-2026:19453
Red Hat Enterprise Linux AppStream TUS (v.8.8)Fixed RHSA-2026:18053
Red Hat Enterprise Linux CRB (v. 8)Fixed RHSA-2026:13830
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)Fixed RHSA-2026:13498, RHSA-2026:19149
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)Fixed RHSA-2026:13857, RHSA-2026:19364
Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)Fixed RHSA-2026:17602
Red Hat Enterprise Linux Server (v. 7 ELS)Fixed RHSA-2026:26564
Red Hat Enterprise Linux Server Optional (v. 7 ELS)Fixed RHSA-2026:26564

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-27857
  2. 2026-10-03 Alias added: GHSA-j26c-8p6m-gpfj

References

Advisory 1

  • TI-2026-22201 When safe filter is used with variable expansion, all following pipelines on the same… CVSS 3.1CRITICAL 9.1
  • TI-2026-22208 Uncontrolled resource consumption in Open-Xchange GmbH OX Dovecot Pro CVSS 3.1HIGH 7.5
  • TI-2025-36674 Improper input validation in Open-Xchange GmbH OX Dovecot Pro CVSS 3.1HIGH 7.5
  • TI-2025-36670 Improper input validation in Open-Xchange GmbH OX Dovecot Pro CVSS 3.1HIGH 7.5
  • TI-2026-19360 SQL injection in Open-Xchange GmbH OX Dovecot Pro CVSS 3.1HIGH 8.2
  • TI-2026-22206 Improper authentication in Open-Xchange GmbH OX Dovecot Pro CVSS 3.1HIGH 7.4
See all 15 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences