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CERT Coordination Center

Barracuda Web Filter insecurely performs SSL inspection

Vulnerability Note VU#534407

Original Release Date: 2015-04-28 | Last Revised: 2015-04-28


Barracuda Web Filter prior to version does not properly check upstream certificate validity when performing SSL inspection, and delivers one of three default root CA certificates across multiple machines for SSL inspection.


According to Barracuda Networks, the Barracuda Web Filter is a "comprehensive solution for web security and management" with many features, including the ability to provide "visibility into SSL-encrypted traffic". This SSL inspection feature of the Barracuda Web Filter is vulnerable to multiple issues.

Incomplete validation of upstream certificate validity - CVE-2015-0961

Barracuda Web Filter versions between 7.0 and do not check upstream certificate validity when performing SSL inspection.

Shared root CA certificate - CVE-2015-0962

Barracuda Web Filter versions between 7.0 and ship one of three different default certificates that are shared across multiple machine for use in the SSL Inspection feature.

Users who have configured SSL Inspection on a Barracuda Web Filter may be affected. Beginning in version, Barracuda Web Filter verifies certificate validity and generates a unique default certificate for each appliance.

Barracuda Networks has released a security advisory with more details. For more information on the impact of these issues on SSL inspection, please see Will Dormann's CERT/CC blog post on SSL Inspection.

The CVSS score below is based on CVE-2015-0962.


The impact of either CVE-2015-0961 or CVE-2015-0962 may allow an attacker to successfully achieve a man-in-the-middle (MITM) attack without the client knowing it.


Update the firmware

Barracuda Networks has released firmware version on April 16th, 2015 to address these issues. Affected users should upgrade to firmware or later as soon as possible.

Users who have deployed an affected service using the default certificate supplied with the appliance will need to deploy a new client certificate to their clients and remove the previously deployed certificate. Instructions for deploying and removing client certificates are available at

Check that old shared certificates are removed

Barracuda has also provided, a site that will show users if their browser trusts any of the shared default certificates and includes instructions for removing the certificates from the browser trust store if necessary.

Vendor Information


Barracuda Networks Affected

Updated:  April 21, 2015

Statement Date:   April 16, 2015



Vendor Statement

We have not received a statement from the vendor.

Vendor Information

We are not aware of further vendor information regarding this vulnerability.

CVSS Metrics

Group Score Vector
Base 8.8 AV:N/AC:M/Au:N/C:C/I:C/A:N
Temporal 6.9 E:POC/RL:OF/RC:C
Environmental 5.2 CDP:ND/TD:M/CR:ND/IR:ND/AR:ND



Thanks to Barracuda Networks for promptly addressing these issues and contacting the CERT/CC to coordinate disclosure.

This document was written by Garret Wassermann.

Other Information

CVE IDs: CVE-2015-0961, CVE-2015-0962
Date Public: 2015-04-28
Date First Published: 2015-04-28
Date Last Updated: 2015-04-28 17:08 UTC
Document Revision: 28

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