CVE-2025-27414: MinIO SFTP authentication bypass due to improperly trusted SSH key
Summary A bug in evaluating the trust of the SSH key used in an SFTP connection to MinIO allows authentication bypass and unauthorized data access.
Details
On a MinIO server with SFTP access configured and using LDAP as an external identity provider, MinIO supports SSH key based authentication for SFTP connections when the user has the sshPublicKey attribute set in their LDAP server. The server trusts the client's key only when the public key is the same as the sshPublicKey attribute.
Due to the bug, when the user has no sshPublicKey property in LDAP, the server ends up trusting the key allowing the client to perform any FTP operations allowed by the MinIO access policies associated with the LDAP user (or any of their groups).
The bug was introduced in https://github.com/minio/minio/commit/91e1487de45720753c9e9e4c02b1bd16b7e452fa.
Impact
The following requirements must be met to exploit this vulnerability:
1. MinIO server must be configured to allow SFTP access and use LDAP as an external identity provider. 2. Knowledge of an LDAP username that does not have the sshPublicKey property set. 3. Such an LDAP username or one of their groups must also have some MinIO access policy configured.
When this bug is successfully exploited, the attacker can perform any FTP operations (i.e. reading, writing, deleting and listing objects) allowed by the access policy associated with the LDAP user account (and their groups).
Other sources
MinIO is a high performance object storage. Starting in RELEASE.2024-06-06T09-36-42Z and prior to RELEASE.2025-02-28T09-55-16Z, a bug in evaluating the trust of the SSH key used in an SFTP connection to MinIO allows authentication bypass and unauthorized data access. On a MinIO server with SFTP access configured and using LDAP as an external identity provider, MinIO supports SSH key based authentication for SFTP connections when the user has the sshPublicKey attribute set in their LDAP server. The server trusts the client's key only when the public key is the same as the sshPublicKey attribute. Due to the bug, when the user has no sshPublicKey property in LDAP, the server ends up trusting the key allowing the client to perform any FTP operations allowed by the MinIO access policies associated with the LDAP user (or any of their groups). Three requirements must be met in order to exploit the vulnerability. First, the MinIO server must be configured to allow SFTP access and use LDAP as an external identity provider. Second, the attacker must have knowledge of an LDAP username that does not have the sshPublicKey property set. Third, such an LDAP username or one of their groups must also have some MinIO access policy configured. When this bug is successfully exploited, the attacker can perform any FTP operations (i.e. reading, writing, deleting and listing objects) allowed by the access policy associated with the LDAP user account (and their groups). Version 1.2.0 fixes the issue.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
go/github.com/minio/minioto a version that resolves this vulnerability.Fixed in 0.0.0-20250227184332-4c71f1b4ec0f - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 1.2.0 - Configuration
Ensure MinIO is configured to allow SFTP access and use LDAP as the external identity provider (as described in the advisory: this is the affected setup where SSH key trust is evaluated against LDAP).
MinIO server SFTP access configuration = enabled - Configuration
Set the sshPublicKey attribute in LDAP for any LDAP username (or one of their groups) that also has MinIO access policies, since the bypass occurs when sshPublicKey is not set.
LDAP user entries sshPublicKey attribute presence = set for all LDAP users/groups that have MinIO access policies
Event History
Frequently Asked Questions
What is the severity of CVE-2025-27414?
The severity of CVE-2025-27414 is considered high due to the potential for authentication bypass and unauthorized data access.
How do I fix CVE-2025-27414?
To fix CVE-2025-27414, upgrade MinIO to a version released after RELEASE.2025-02-28T09-55-16Z.
What systems are affected by CVE-2025-27414?
CVE-2025-27414 affects MinIO versions from RELEASE.2024-06-06T09-36-42Z to RELEASE.2025-02-28T09-55-16Z.
What vulnerability does CVE-2025-27414 address?
CVE-2025-27414 addresses a vulnerability that allows for authentication bypass through improper evaluation of SSH keys in SFTP connections.
Can CVE-2025-27414 lead to data breaches?
Yes, CVE-2025-27414 can lead to data breaches as it allows unauthorized access to sensitive data on MinIO servers.