CVE-2026-27856
Timing Oracle Vulnerability in Doveadm Enables Credential Disclosure
Publication date: 2026-03-27
Last updated on: 2026-04-29
Assigner: Open-Xchange
Description
Description
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| dovecot | dovecot | to 2.4.3 (exc) |
| open-xchange | dovecot | From 3.0.0 (inc) to 3.0.5 (exc) |
| open-xchange | dovecot | From 3.1.0 (inc) to 3.1.4 (exc) |
| open-xchange | dovecot | to 2.3.22.1 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-287 | When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability involves the Doveadm component verifying credentials using a direct comparison method that is vulnerable to a timing oracle attack.
An attacker can exploit this timing difference to determine the configured credentials.
Once the attacker figures out the credentials, they can gain full access to the affected component.
How can this vulnerability impact me? :
If exploited, this vulnerability can allow an attacker to obtain the credentials for the Doveadm component.
With these credentials, the attacker can gain full access to the affected component, potentially compromising the system.
This could lead to unauthorized access and control over the services provided by Doveadm.
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability involves a timing oracle attack on doveadm credentials due to direct comparison verification. Detection would involve monitoring access attempts to the doveadm HTTP service port and analyzing for unusual timing patterns or repeated authentication attempts that could indicate exploitation attempts.
Since no publicly available exploits are known and no specific detection commands are provided, general network monitoring and logging of access to the doveadm HTTP service port is recommended.
What immediate steps should I take to mitigate this vulnerability?
- Limit access to the doveadm HTTP service port to trusted hosts only.
- Install the fixed version of the software that addresses this vulnerability.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
The vulnerability allows an attacker to determine configured credentials through a timing oracle attack, potentially leading to full access to the affected component. This unauthorized access could result in exposure or compromise of sensitive data.
Such unauthorized access and potential data compromise may negatively impact compliance with standards and regulations like GDPR and HIPAA, which require protection of personal and sensitive information.
Mitigation steps include limiting access to the doveadm HTTP service port and installing a fixed version, which are necessary to maintain compliance and reduce risk.