Read the docs
TI-2026-30394 Aliases CVE-2026-42006GHSA-h665-fh45-xq6r

Uncontrolled resource consumption in Open-Xchange GmbH OX Dovecot Pro

Priority LOW 21CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · Low
Fix status
Partial Red Hat: 18 fixed, 1 without a fix

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

Summary

An attacker can cause uncontrolled memory usage with excessive bracing over IMAP. The fix in CVE-2026-27857 was incomplete, only blocking one way of doing this, so there was still another way left open. In particular, the fix was for closing braces, but you could still use open braces to bypass the limit. Using excessive bracing, attacker can cause memory usage up to configured memory limit. Install fixed version, or configure vsz_limit for imap process to low value. No publicly available exploits are known.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00621 50th percentileScored 2026-11-07
Fix Partial Red Hat: 11 advisoriesRed Hat: 18 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 3.0.5; up to 3.1.4; up to 2.4.3—No fix listedCNA
  • OX Dovecot Pro VendorOpen-Xchange GmbH Affected up to 3.0.5; up to 3.1.4; up to 2.4.3 Fixed in — No fix listed CNA

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:*before 2.4.4VulnerableThe Dovecot Project
cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*before 3.1.5VulnerableOpen-Xchange GmbH
  • cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:* Versions before 2.4.4 Vulnerable ·The Dovecot Project
  • cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:* Versions before 3.1.5 Vulnerable ·Open-Xchange GmbH

Remediation

Red Hat 11 advisories

  • RHSA-2026:49513 Released 2026-08-03 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux Server (v. 7 ELS) dovecot-1:2.2.36-8.el7_9.2, dovecot-1:2.2.36-8.el7_9.2.ppc
  • RHSA-2026:46532 Released 2026-07-27 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream (v. 8) dovecot-1:2.3.16-8.el8_10, dovecot-mysql-1:2.3.16-8.el8_10, dovecot-pgsql-1:2.3.16-8.el8_10 +1
    • Red Hat Enterprise Linux CRB (v. 8) dovecot-1:2.3.16-8.el8_10, dovecot-devel-1:2.3.16-8.el8_10
  • RHSA-2026:46381 Released 2026-07-27 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream E4S (v.8.8) dovecot-1:2.3.16-3.el8_8.2
    • Red Hat Enterprise Linux AppStream TUS (v.8.8) dovecot-1:2.3.16-3.el8_8.2
Show 8 more Red Hat advisories
  • RHSA-2026:46379 Released 2026-07-27 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream AUS (v.8.6) dovecot-1:2.3.16-2.el8_6.2
    • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) dovecot-1:2.3.16-2.el8_6.2
  • RHSA-2026:46380 Released 2026-07-27 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream AUS (v.8.4) dovecot-1:2.3.8-9.el8_4.2
    • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) dovecot-1:2.3.8-9.el8_4.2
  • RHSA-2026:44355 Released 2026-07-23 · Red Hat rating Important
    dovecot security update
    • Red Hat CodeReady Linux Builder EUS (v.9.6) dovecot-1:2.3.16-15.el9_6.2
    • Red Hat Enterprise Linux AppStream EUS (v.9.6) dovecot-1:2.3.16-15.el9_6.2
  • RHSA-2026:44373 Released 2026-07-23 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream E4S (v.9.2) dovecot-1:2.3.16-8.el9_2.3
  • RHSA-2026:44357 Released 2026-07-23 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream E4S (v.9.4) dovecot-1:2.3.16-11.el9_4.3
  • RHSA-2026:42091 Released 2026-07-20 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream EUS (v. 10.0) dovecot-1:2.3.21-16.el10_0.2
  • RHSA-2026:41988 Released 2026-07-20 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream (v. 10) dovecot-1:2.3.21-19.el10_2.1, dovecot-mysql-1:2.3.21-19.el10_2.1, dovecot-pgsql-1:2.3.21-19.el10_2.1 +1
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) dovecot-devel-1:2.3.21-19.el10_2.1
  • RHSA-2026:41905 Released 2026-07-20 · Red Hat rating Important
    dovecot security update
    • Red Hat Enterprise Linux AppStream (v. 9) dovecot-1:2.3.16-18.el9_8.1, dovecot-mysql-1:2.3.16-18.el9_8.1, dovecot-pgsql-1:2.3.16-18.el9_8.1 +1
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) dovecot-1:2.3.16-18.el9_8.1, dovecot-devel-1:2.3.16-18.el9_8.1

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Advisory ·

    Open-Xchange OX Dovecot Pro — documentation.open-xchange.com/dovecot/security/advisories/…

    5 records Highest priority Priority MEDIUM 1 MEDIUM, 4 LOW

    Other records, highest priority first

    • TI-2026-22201 When safe filter is used with variable expansion, all following pipelines on the same…Priority MEDIUM 41
    • TI-2026-25985 Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake…Priority LOW 31
    • TI-2026-28859 Uncontrolled resource consumption in Open-Xchange GmbH OX Dovecot ProPriority LOW 29
    Show all 5 records → Advisory →

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: Out of support scope
Red Hat CodeReady Linux Builder EUS (v.9.6)Fixed RHSA-2026:44355
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:41988
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2026:46532
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2026:41905
Red Hat Enterprise Linux AppStream AUS (v.8.4)Fixed RHSA-2026:46380
Red Hat Enterprise Linux AppStream AUS (v.8.6)Fixed RHSA-2026:46379
Red Hat Enterprise Linux AppStream E4S (v.8.8)Fixed RHSA-2026:46381
Red Hat Enterprise Linux AppStream E4S (v.9.2)Fixed RHSA-2026:44373
Red Hat Enterprise Linux AppStream E4S (v.9.4)Fixed RHSA-2026:44357
Red Hat Enterprise Linux AppStream EUS (v. 10.0)Fixed RHSA-2026:42091
Red Hat Enterprise Linux AppStream EUS (v.9.6)Fixed RHSA-2026:44355
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)Fixed RHSA-2026:46380
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6)Fixed RHSA-2026:46379
Red Hat Enterprise Linux AppStream TUS (v.8.8)Fixed RHSA-2026:46381
Red Hat Enterprise Linux CRB (v. 8)Fixed RHSA-2026:46532
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)Fixed RHSA-2026:41988
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)Fixed RHSA-2026:41905
Red Hat Enterprise Linux Server (v. 7 ELS)Fixed RHSA-2026:49513
Not affected: 14 products
  • Red Hat CodeReady Linux Builder EUS (v.9.6)
  • Red Hat Enterprise Linux AppStream AUS (v.8.4)
  • Red Hat Enterprise Linux AppStream AUS (v.8.6)
  • Red Hat Enterprise Linux AppStream E4S (v.8.8)
  • Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • Red Hat Enterprise Linux AppStream E4S (v.9.4)
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • Red Hat Enterprise Linux AppStream EUS (v.9.6)
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6)
  • Red Hat Enterprise Linux AppStream TUS (v.8.8)
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)
  • Red Hat Enterprise Linux Server (v. 7 ELS)
  • Red Hat Enterprise Linux Server Optional (v. 7 ELS)

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-42006
  2. 2026-10-03 Alias added: GHSA-h665-fh45-xq6r
  3. 2026-10-25 EPSS moved to the below the 50th percentile
  4. 2026-11-07 EPSS moved to the 50th–90th percentile

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