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
02 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
03 Exploitation and scoring
- Exploitation
- Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
- SSVC decision
- ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
- AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
- Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
- EPSS probability
- 0.67% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 52.0% of scored records. A rank, not a probability.
- NVD base score
- 7.5 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVD analysis status
- Modified. NVD last modified this record on 2026-10-26.
- Red Hat severity
- Important. Red Hat's rating for its own products, not a CVSS rating.
Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.
04 Metadata
- Published
- 2026-03-27 08:10Z7 MO AGO
- Last updated
- 2026-07-15 01:12Z3 MO AGO
- Reserved
- 2026-02-24
- Assigning CNA
- OX
- Record state
- PUBLISHED
- Severity
- Medium (CVSS 4.3)
- CNA CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
- Weaknesses
- Data version
- 5.2
- Document digest
- 6a60645a9f9abe814d0d6dadbc9ba09aa04b5be1843dfabb99caa970b1b797d0
05 Affected products
06 References
- documentation.open-xchange.comhttps://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json
- access.redhat.comhttps://access.redhat.com/security/cve/CVE-2026-27857
- bugzilla.redhat.comRHBZ#2452179https://bugzilla.redhat.com/show_bug.cgi?id=2452179
- security.access.redhat.comhttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27857.json
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:26564
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:17602
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:13498
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:19149
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:13830
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:19455
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:19453
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:18053
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:17630
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:17628
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:17625
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:17626
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:13857
- access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:19364
07 Fixed in
AlmaLinux 8
- dovecot Fixed in 1:2.3.16-7.el8_10
- dovecot-devel Fixed in 1:2.3.16-7.el8_10
- dovecot-mysql Fixed in 1:2.3.16-7.el8_10
- dovecot-pgsql Fixed in 1:2.3.16-7.el8_10
- dovecot-pigeonhole Fixed in 1:2.3.16-7.el8_10
Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.
AlmaLinux 9
- dovecot Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.16-15.el9_7.1
- Affected before 1:2.3.16-18.el9_8
- dovecot-devel Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.16-15.el9_7.1
- Affected before 1:2.3.16-18.el9_8
- dovecot-mysql Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.16-15.el9_7.1
- Affected before 1:2.3.16-18.el9_8
- dovecot-pgsql Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.16-15.el9_7.1
- Affected before 1:2.3.16-18.el9_8
- dovecot-pigeonhole Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.16-15.el9_7.1
- Affected before 1:2.3.16-18.el9_8
Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.
AlmaLinux 10
- dovecot Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.21-16.el10_1.1
- Affected before 1:2.3.21-19.el10_2
- dovecot-devel Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.21-16.el10_1.1
- Affected before 1:2.3.21-19.el10_2
- dovecot-mysql Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.21-16.el10_1.1
- Affected before 1:2.3.21-19.el10_2
- dovecot-pgsql Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.21-16.el10_1.1
- Affected before 1:2.3.21-19.el10_2
- dovecot-pigeonhole Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.21-16.el10_1.1
- Affected before 1:2.3.21-19.el10_2
Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.
CloudLinux 8
- dovecot Fixed in 1:2.3.16-7.el8_10
- dovecot-devel Fixed in 1:2.3.16-7.el8_10
- dovecot-mysql Fixed in 1:2.3.16-7.el8_10
- dovecot-pgsql Fixed in 1:2.3.16-7.el8_10
- dovecot-pigeonhole Fixed in 1:2.3.16-7.el8_10
Derived from AlmaLinux 8. Partial coverage: only packages taken from AlmaLinux 8 are listed.
Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.
CloudLinux 9
- dovecot Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.16-15.el9_7.1
- Affected before 1:2.3.16-18.el9_8
- dovecot-devel Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.16-15.el9_7.1
- Affected before 1:2.3.16-18.el9_8
- dovecot-mysql Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.16-15.el9_7.1
- Affected before 1:2.3.16-18.el9_8
- dovecot-pgsql Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.16-15.el9_7.1
- Affected before 1:2.3.16-18.el9_8
- dovecot-pigeonhole Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.16-15.el9_7.1
- Affected before 1:2.3.16-18.el9_8
Derived from AlmaLinux 9. Partial coverage: only packages taken from AlmaLinux 9 are listed.
Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.
CloudLinux 10
- dovecot Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.21-16.el10_1.1
- Affected before 1:2.3.21-19.el10_2
- dovecot-devel Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.21-16.el10_1.1
- Affected before 1:2.3.21-19.el10_2
- dovecot-mysql Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.21-16.el10_1.1
- Affected before 1:2.3.21-19.el10_2
- dovecot-pgsql Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.21-16.el10_1.1
- Affected before 1:2.3.21-19.el10_2
- dovecot-pigeonhole Fixed
A version is affected if any line below covers it.
- Affected before 1:2.3.21-16.el10_1.1
- Affected before 1:2.3.21-19.el10_2
Derived from AlmaLinux 10. Partial coverage: only packages taken from AlmaLinux 10 are listed.
Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.
Debian 12
- dovecot Fixed in 1:2.3.19.1+dfsg1-2.1+deb12u2
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 13
- dovecot Fixed in 1:2.4.1+dfsg1-6+deb13u4
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 14
- dovecot Fixed in 1:2.4.3+dfsg1-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 20.04 LTS
- dovecot No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 22.04 LTS
- dovecot Fixed in 1:2.3.16+dfsg1-3ubuntu2.7
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 24.04 LTS
- dovecot Fixed in 1:2.3.21+dfsg1-2ubuntu6.3
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 25.10
- dovecot Fixed in 1:2.4.1+dfsg1-5ubuntu4.1
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.