High severity · published Mar 27, 2026
CVE-2026-27858
Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory
7.5
CVSS
0.8%
EPSS
No
On KEV
Description
Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory.
Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access to managesieve protocol, or install fixed version. No publicly available exploits are known.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.8% · higher than 57% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
OD
OX Dovecot Pro · Open-Xchange GmbH
through 2.3.0; through 3.1.0; through 2.4.0 · source: vendor
DO
Dovecot · Dovecot
before 2.4.3 · source: NVD
RH
Red Hat Enterprise Linux 10 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 10.0 Extended Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 6 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 7 Extended Lifecycle Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.6 Telecommunications Update Service · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27858
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-27858
Vendor Advisory
https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:13498
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:13830
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:13857
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:17602
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:17625
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