CVE Tools
Sign in

CVE-2026-27855

Published: Mar 27, 2026Updated: Apr 29, 2026 Sources: CVE List NVDCWE-294
NVD MITRE
6.8CVSSMEDIUM
EPSS Score
0.3%
Top 74.6%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

Dovecot OTP authentication is vulnerable to replay attack under specific conditions. If auth cache is enabled, and username is altered in passdb, then OTP credentials can be cached so that same OTP reply is valid. An attacker able to observe an OTP exchange is able to log in as the user. If authentication happens over unsecure connection, switch to SCRAM protocol. Alternatively ensure the communcations are secured, and if possible switch to OAUTH2 or SCRAM. No publicly available exploits are known.

CVSS Vector Breakdown

AV:NAC:HPR:NUI:RS:UC:HI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:NAvailability
None
Open in CVSS calculator →

Weaknesses

CWE-294

Affected Products

dovecotdovecot
On-premWeb App
Communications / email-server-client
dovecotopen-xchangeCommunications
OX Dovecot ProOpen-Xchange GmbH
On-prem
Enterprise Software / collaboration-groupware
dovecotoss-projectCommunicationsaka dovecot, pigeonhole
open-xchangecommercialDECommunicationsaka open-xchange gmbh, ox
open-xchange gmbhcommercialDEEnterprise Softwareaka open-xchange

Attack Graph

Products CVE Techniques Tactics

Click technique nodes to view MITRE ATT&CK details. Scroll to zoom, drag to pan.

Exploitability

Official Patch Available

MITRE ATT&CK

1 technique
Defense Evasion
View detailed technique mapping

References

https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json
documentation.open-xchange.com

Timeline

Published
Mar 27, 2026
Last Updated
Apr 29, 2026

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2026-27855 and every CVE in our database. Create a free account — no credit card required.

Create Free Account
Plain-language analysis
Impact assessment and exploitation scenario in plain English
Attack graph visualization
Interactive attack path and kill chain mapping
Exploit details & PoC links
ExploitDB, Metasploit, GitHub PoCs with direct links
Nuclei scanner templates
Ready-to-use vulnerability scanner templates
Full remediation guide
Patch instructions, workarounds, and compliance impact
Interactive AI chat
Ask questions about this vulnerability in natural language
Related vulnerabilities
Semantically similar CVEs and attack patterns
REST API & MCP access
Integrate vulnerability data into your workflows