CVE-2026-27851
Description
A flaw was found in Dovecot. When the safe filter is used with variable expansion, subsequent pipelines on the same string are incorrectly interpreted as safe, allowing unsafe data to be unescaped. This can enable SQL (Structured Query Language) or LDAP (Lightweight Directory Access Protocol) injection attacks when used in authentication, potentially leading to unauthorized access or information disclosure.
Statement
This issue is classified as Important severity primarily because:
Exploitation requires a specific configuration where the safe filter is used in combination with variable expansion and subsequent pipelines on the same string during the authentication process.
Successfully bypassing the safe filter allows unsafe data to be unescaped, enabling an attacker to execute SQL or LDAP injection attacks, which can lead directly to unauthorized access and significant information disclosure.
Mitigation
To mitigate this issue, avoid using the 'safe filter' feature in Dovecot configurations that involve variable expansion.
Administrators should review Dovecot configuration files, typically found in `/etc/dovecot/conf.d/`, to identify and disable or modify any configurations that utilize the `safe filter` with variable expansion.
A restart of the Dovecot service is necessary for these changes to take effect and may impact services relying on this feature.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.4 | 9.1 | 7.4 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | Low | High |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | None | None | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Red Hat CVSS v3 Score Explanation
Exploitation requires a specific configuration where the safe filter is used in combination with variable expansion and subsequent pipelines on the same string during the authentication process.
Understanding the Weakness (CWE)
Confidentiality,Integrity,Availability
Technical Impact: Execute Unauthorized Code or Commands
Adversaries could execute system commands, typically by changing the SQL statement to redirect output to a file that can then be executed.
Confidentiality
Technical Impact: Read Application Data
Since SQL databases generally hold sensitive data, loss of confidentiality is a frequent problem with SQL injection vulnerabilities.
Authentication
Technical Impact: Gain Privileges or Assume Identity; Bypass Protection Mechanism
If poor SQL commands are used to check user names and passwords or perform other kinds of authentication, it may be possible to connect to the product as another user with no previous knowledge of the password.
Access Control
Technical Impact: Bypass Protection Mechanism
If authorization information is held in a SQL database, it may be possible to change this information through the successful exploitation of a SQL injection vulnerability.
Integrity
Technical Impact: Modify Application Data
Just as it may be possible to read sensitive information, it is also possible to modify or even delete this information with a SQL injection attack.
Frequently Asked Questions
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