CVE-2017-2619

Impact:
Moderate
Public Date:
2017-03-23
IAVA:
2017-A-0085
CWE:
CWE-362
Bugzilla:
1429472: CVE-2017-2619 samba: symlink race permits opening files outside share directory
A race condition was found in samba server. A malicious samba client could use this flaw to access files and directories in areas of the server file system not exported under the share definitions.

Find out more about CVE-2017-2619 from the MITRE CVE dictionary dictionary and NIST NVD.

Statement

Red Hat Enterprise Linux 5:
This vulnerability has been rated as having a security impact of Moderate. After evaluation and in accordance with the criteria noted in the product support life cycle, there are no plans to address this issue in an upcoming release. Please contact Red Hat Support for further information.

Red Hat Enterprise Linux 6:
This vulnerability has been rated as having a security impact of Moderate. After evaluation and in accordance with the criteria noted in the product support life cycle, there are no plans to address this issue in an upcoming release. Please contact Red Hat Support for further information.

CVSS v3 metrics

CVSS3 Base Score 5.9
CVSS3 Base Metrics CVSS:3.0/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:L
Attack Vector Network
Attack Complexity High
Privileges Required Low
User Interaction Required
Scope Unchanged
Confidentiality High
Integrity Impact Low
Availability Impact Low

Red Hat Security Errata

Platform Errata Release Date
Red Hat Gluster 3.3 Samba on RHEL-6 (samba) RHSA-2017:2778 2017-09-21
Red Hat Gluster 3.2 Samba on RHEL-7 (samba) RHSA-2017:2338 2017-08-01
Red Hat Enterprise Linux 6 (samba) RHSA-2017:2789 2017-09-21
Red Hat Enterprise Linux 7 (samba) RHSA-2017:1265 2017-05-22

Affected Packages State

Platform Package State
Red Hat Enterprise Linux 6 samba4 Will not fix
Red Hat Enterprise Linux 5 samba Will not fix
Red Hat Enterprise Linux 5 samba3x Will not fix
Unless explicitly stated as not affected, all previous versions of packages in any minor update stream of a product listed here should be assumed vulnerable, although may not have been subject to full analysis.

Acknowledgements

Red Hat would like to thank the Samba project for reporting this issue. Upstream acknowledges Jann Horn (Google) as the original reporter.

Mitigation

Add the parameter:

unix extensions = no

to the [global] section of your smb.conf and restart smbd. This prevents SMB1 clients from creating symlinks on the exported file system using SMB1.

However, if the same region of the file system is also exported using NFS, NFS clients can create symlinks that potentially can also hit the race condition. For non-patched versions of Samba we recommend only exporting areas of the file system by either SMB or NFS, not both.

External References

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