7.5
HIGH
CVSS 3.1
CVE-2026-27858
Dovecot Managesieve Denial of Service and Memory Exhaustion
Overview
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.
Details
INFO
Published Date :
March 27, 2026, 9:16 a.m.
Last Modified :
June 30, 2026, 3:17 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework
for assessing the severity of vulnerabilities in software and systems.
We collect and displays CVSS scores from various sources for each CVE.
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 8ce71d90-2354-404b-a86e-bec2cc4e6981 | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c |
Solution
Denial of service by memory exhaustion. Protect access or install update.
- Protect access to managesieve protocol.
- Install the fixed version of managesieve.
References
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-27858.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-27858 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-27858
weaknesses.
CAPEC-147: XML Ping of the Death XML Ping of the Death
CAPEC-227: Sustained Client Engagement Sustained Client Engagement
CAPEC-492: Regular Expression Exponential Blowup Regular Expression Exponential Blowup
CAPEC-125: Flooding Flooding
CAPEC-130: Excessive Allocation Excessive Allocation
CAPEC-147: XML Ping of the Death XML Ping of the Death
CAPEC-197: Exponential Data Expansion Exponential Data Expansion
CAPEC-229: Serialized Data Parameter Blowup Serialized Data Parameter Blowup
CAPEC-230: Serialized Data with Nested Payloads Serialized Data with Nested Payloads
CAPEC-231: Oversized Serialized Data Payloads Oversized Serialized Data Payloads
CAPEC-469: HTTP DoS HTTP DoS
CAPEC-482: TCP Flood TCP Flood
CAPEC-486: UDP Flood UDP Flood
CAPEC-487: ICMP Flood ICMP Flood
CAPEC-488: HTTP Flood HTTP Flood
CAPEC-489: SSL Flood SSL Flood
CAPEC-490: Amplification Amplification
CAPEC-491: Quadratic Data Expansion Quadratic Data Expansion
CAPEC-493: SOAP Array Blowup SOAP Array Blowup
CAPEC-494: TCP Fragmentation TCP Fragmentation
CAPEC-495: UDP Fragmentation UDP Fragmentation
CAPEC-496: ICMP Fragmentation ICMP Fragmentation
CAPEC-528: XML Flood XML Flood
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-27858 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-27858 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Jun. 30, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:/o:redhat:rhel_els:7'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux Server (v. 7 ELS)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/o:redhat:rhel_els:7'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux Server Optional (v. 7 ELS)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux_eus:10.0'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream EUS (v. 10.0)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:10.1', 'cpe:/o:redhat:enterprise_linux:10.2'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream (v. 10)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:enterprise_linux:8::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream (v. 8)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:rhel_aus:8.4::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream AUS (v.8.4)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:rhel_eus_long_life:8.4::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:rhel_aus:8.6::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream AUS (v.8.6)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:rhel_e4s:8.6::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream E4S (v.8.6)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:rhel_tus:8.6::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream TUS (v.8.6)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:rhel_e4s:8.8::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream E4S (v.8.8)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:rhel_tus:8.8::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream TUS (v.8.8)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:rhel_e4s:9.0::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream E4S (v.9.0)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:rhel_e4s:9.2::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream E4S (v.9.2)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:rhel_eus:9.4::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream EUS (v.9.4)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:rhel_eus:9.6::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream EUS (v.9.6)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:enterprise_linux:9::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream (v. 9)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux_eus:10.0'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:10.1', 'cpe:/o:redhat:enterprise_linux:10.2'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:enterprise_linux:8::crb'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux CRB (v. 8)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:rhel_eus:9.4::crb'], 'vendor': 'Red Hat', 'product': 'Red Hat CodeReady Linux Builder EUS (v.9.4)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:rhel_eus:9.6::crb'], 'vendor': 'Red Hat', 'product': 'Red Hat CodeReady Linux Builder EUS (v.9.6)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:enterprise_linux:9::crb'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:6'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 6', 'defaultStatus': 'affected'}] Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-770 Added Reference https://access.redhat.com/errata/RHSA-2026:13498 Added Reference https://access.redhat.com/errata/RHSA-2026:13830 Added Reference https://access.redhat.com/errata/RHSA-2026:13857 Added Reference https://access.redhat.com/errata/RHSA-2026:17602 Added Reference https://access.redhat.com/errata/RHSA-2026:17625 Added Reference https://access.redhat.com/errata/RHSA-2026:17626 Added Reference https://access.redhat.com/errata/RHSA-2026:17628 Added Reference https://access.redhat.com/errata/RHSA-2026:17630 Added Reference https://access.redhat.com/errata/RHSA-2026:18053 Added Reference https://access.redhat.com/errata/RHSA-2026:19149 Added Reference https://access.redhat.com/errata/RHSA-2026:19364 Added Reference https://access.redhat.com/errata/RHSA-2026:19453 Added Reference https://access.redhat.com/errata/RHSA-2026:19455 Added Reference https://access.redhat.com/errata/RHSA-2026:26564 Added Reference https://access.redhat.com/security/cve/CVE-2026-27858 Added Reference https://bugzilla.redhat.com/show_bug.cgi?id=2452175 Added Reference https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27858.json -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Open-Xchange GmbH', 'modules': ['core'], 'product': 'OX Dovecot Pro', 'versions': [{'status': 'affected', 'version': '0', 'versionType': 'semver', 'lessThanOrEqual': '2.3.0'}, {'status': 'affected', 'version': '0', 'versionType': 'semver', 'lessThanOrEqual': '3.1.0'}, {'status': 'affected', 'version': '0', 'versionType': 'semver', 'lessThanOrEqual': '2.4.0'}], 'defaultStatus': 'unaffected'}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-27858', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-03-27T12:36:26.526829Z'} -
Initial Analysis by [email protected]
Apr. 30, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:* versions up to (excluding) 2.4.3 *cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:* versions from (including) 3.0.0 up to (excluding) 3.0.5 *cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:* versions from (including) 3.1.0 up to (excluding) 3.1.4 *cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:* versions up to (excluding) 2.3.22.1 Added Reference Type Open-Xchange: https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json Types: Vendor Advisory -
New CVE Received by [email protected]
Mar. 27, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-400 Added Reference https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json
EPSS is a daily estimate of the probability of exploitation activity
being observed over the next 30 days. Following chart shows the EPSS
score history of the vulnerability.