CVE Vulnerabilities


Exposure of Sensitive Information to an Unauthorized Actor

Published: Jan 27, 2017 | Modified: Jan 05, 2018
CVSS 3.x
CVSS 2.x

Incorrect processing of responses to If-None-Modified HTTP conditional requests in Squid HTTP Proxy 3.1.10 through 3.1.23, through 3.5.22, and 4.0.1 through 4.0.16 leads to client-specific Cookie data being leaked to other clients. Attack requests can easily be crafted by a client to probe a cache for this information.


The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.

Affected Software

Name Vendor Start Version End Version
Debian_linux Debian 8.0 8.0
Red Hat Enterprise Linux 6 RedHat squid34-7:3.4.14-9.el6_8.4 *
Red Hat Enterprise Linux 7 RedHat squid-7:3.5.20-2.el7_3.2 *
Squid3 Ubuntu devel *
Squid3 Ubuntu esm-infra/xenial *
Squid3 Ubuntu precise *
Squid3 Ubuntu trusty *
Squid3 Ubuntu upstream *
Squid3 Ubuntu xenial *
Squid3 Ubuntu yakkety *

Extended Description

There are many different kinds of mistakes that introduce information exposures. The severity of the error can range widely, depending on the context in which the product operates, the type of sensitive information that is revealed, and the benefits it may provide to an attacker. Some kinds of sensitive information include:

Information might be sensitive to different parties, each of which may have their own expectations for whether the information should be protected. These parties include:

Information exposures can occur in different ways:

It is common practice to describe any loss of confidentiality as an “information exposure,” but this can lead to overuse of CWE-200 in CWE mapping. From the CWE perspective, loss of confidentiality is a technical impact that can arise from dozens of different weaknesses, such as insecure file permissions or out-of-bounds read. CWE-200 and its lower-level descendants are intended to cover the mistakes that occur in behaviors that explicitly manage, store, transfer, or cleanse sensitive information.

Potential Mitigations

  • Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
  • Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.