CVE-2019-20920

Public on

Last Modified: UTC

ModerateModerate ImpactWhat does this mean?
DescriptionStatementAdditional informationAffected PackagesCVSS Score DetailsWeakness (CWE)FAQ

Description

A flaw was found in nodejs-handlebars, where affected versions of handlebars are vulnerable to arbitrary code execution. The package lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript into the system. This issue is used to run arbitrary code in a server processing Handlebars templates or on a victim's browser (effectively serving as Cross-Site Scripting). The highest threat from this vulnerability is to confidentiality.

A flaw was found in nodejs-handlebars, where affected versions of handlebars are vulnerable to arbitrary code execution. The package lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript into the system. This issue is used to run arbitrary code in a server processing Handlebars templates or on a victim's browser (effectively serving as Cross-Site Scripting). The highest threat from this vulnerability is to confidentiality.

Statement

Red Hat Quay includes Handlebars.js as a development dependency. It does not use Handlebars.js at runtime to process templates, so it has been given a low impact rating. Red Hat Virtualization includes Handlebars.js in two components. In ovirt-engine-ui-extentions, the version used is newer and is not affected by this flaw. In ovirt-web-ui, Handlebars.js is included as a development dependency and is not used at runtime to process templates, so it has been given a low impact rating. Red Hat OpenShift Container Platform (OCP) 4 delivers the kibana package, which includes Handlebars.js. From OCP 4.6, the kibana package is no longer shipped and will not be fixed. The openshift4/ose-logging-kibana6 container includes Handlebars.js directly as container first code. The vulnerable version of Handlebars.js is also included in openshift4/ose-grafana, but as the Grafana instance is in read-only mode, the configuration/dashboards cannot be modified.

Red Hat Quay includes Handlebars.js as a development dependency. It does not use Handlebars.js at runtime to process templates, so it has been given a low impact rating.

Red Hat Virtualization includes Handlebars.js in two components. In ovirt-engine-ui-extentions, the version used is newer and is not affected by this flaw. In ovirt-web-ui, Handlebars.js is included as a development dependency and is not used at runtime to process templates, so it has been given a low impact rating.

Red Hat OpenShift Container Platform (OCP) 4 delivers the kibana package, which includes Handlebars.js. From OCP 4.6, the kibana package is no longer shipped and will not be fixed. The openshift4/ose-logging-kibana6 container includes Handlebars.js directly as container first code. The vulnerable version of Handlebars.js is also included in openshift4/ose-grafana, but as the Grafana instance is in read-only mode, the configuration/dashboards cannot be modified.

Additional information

  • Bugzilla 1882260: nodejs-handlebars: lookup helper fails to properly validate templates allowing for arbitrary JavaScript execution
  • CWE-20: Improper Input Validation
  • FAQ: Frequently asked questions about CVE-2019-20920

Common Vulnerability Scoring System (CVSS) Score Details

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).

CVSS v3 Score Breakdown
Red HatNVD

CVSS v3 Base Score

8.1

8.1

Attack Vector

Network

Network

Attack Complexity

High

High

Privileges Required

None

None

User Interaction

None

None

Scope

Changed

Changed

Confidentiality Impact

High

High

Integrity Impact

Low

Low

Availability Impact

Low

Low

CVSS v3 Vector

Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:L

NVD: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:L

Red Hat CVSS v3 Score Explanation

Proposed changes to NIST's current CVSSv3 scoring: AC:L -> AC:H To exploit this vulnerability an attacker needs to prepare/construct a dedicated malicious template which will be incorrectly validated by the package lookup helper. Hence proposing a change to Attack Complexity (AC) from Low to High. S:U -> S:C An exploited vulnerability can affect various resources, also could lead to arbitrary code execution on a victim's browser. Hence proposing a change to Scope (S) metric from Unchanged to Changed. I:H -> I:L A:H -> A:L As the biggest impact by this vulnerability is to Confidentiality, proposing a reduction of values for the metrics Integrity (I) and Availability (A) from High to Low. We consider this as a Moderate impact flaw.

Proposed changes to NIST's current CVSSv3 scoring:

AC:L -> AC:H To exploit this vulnerability an attacker needs to prepare/construct a dedicated malicious template which will be incorrectly validated by the package lookup helper. Hence proposing a change to Attack Complexity (AC) from Low to High.

S:U -> S:C An exploited vulnerability can affect various resources, also could lead to arbitrary code execution on a victim's browser. Hence proposing a change to Scope (S) metric from Unchanged to Changed.

I:H -> I:L A:H -> A:L As the biggest impact by this vulnerability is to Confidentiality, proposing a reduction of values for the metrics Integrity (I) and Availability (A) from High to Low.

We consider this as a Moderate impact flaw.

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

For open source software shipped by multiple vendors, the CVSS base scores may vary for each vendor's version depending on the version they ship, how they ship it, the platform, and even how the software is compiled. This makes scoring of vulnerabilities difficult for third-party vulnerability databases such as NVD that only provide a single CVSS base score for each vulnerability. Red Hat scores reflect how a vulnerability affects our products specifically.

For more information, see https://access.redhat.com/solutions/762393.

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?

  • "Under investigation" doesn't necessarily mean that the product is affected by this vulnerability. It only means that our Analysis Team is still working on determining whether the product is affected and how it is affected.
  • The term "Affected" means that our Analysis team has determined that this product, such as Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to address this issue in the near future. This includes all minor releases of this product unless noted otherwise in the Statement text.

What can I do if my product is listed as "Will not fix"?

A "will not fix" status means that a fix for an affected product version is not planned or not possible due to complexity, which may create additional risk.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Upgrade to a supported product version that includes a fix for this vulnerability (recommended).
  • Apply a mitigation (if one exists).
  • Open a support case to request a prioritization of releasing a fix for this vulnerability.

What can I do if my product is listed as "Fix deferred"?

A deferred status means that a fix for an affected product version is not guaranteed due to higher-priority development work.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Apply a mitigation (if one exists).
  • Open a support case to request a prioritization of releasing a fix for this vulnerability.
  • Red Hat Engineering focuses on addressing high-priority issues based on their complexity or limited lifecycle support. Therefore, lower-priority issues will not receive immediate fixes.

What is a mitigation?

A mitigation is an action that can be taken to reduce the impact of a security vulnerability, without deploying any fixes.

I have a Red Hat product but it is not in the above list, is it affected?

The listed products were found to include one or more of the components that this vulnerability affects. These products underwent a thorough evaluation to determine their affectedness by this vulnerability. Note that layered products (such as container-based offerings) that consume affected components from any of the products listed in this table may be affected and are not represented.

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

In order to maintain code stability and compatibility, Red Hat usually does not rebase packages to entirely new versions. Instead, we backport fixes and new features to an older version of the package we distribute. This can result in some security scanners that only consider the package version to report the package as vulnerable. To avoid this, we suggest that you use an approved vulnerability scanner from our Red Hat Vulnerability Scanner Certification program.

Want to get errata notifications? Sign up here.