CVE-2018-20821: Medium severity libsass vulnerability

Published Apr 23, 2019
·
Updated

LibSass is vulnerable to a denial of service, caused by uncontrolled recursion in Sass::Parser::parsecssvariablevalue in parser.cpp. By persuading a victim to open a specially-crafted file, a remote attacker could exploit this vulnerability to cause the application to crash.

Other sources

The parsing component in LibSass through 3.5.5 allows attackers to cause a denial-of-service (uncontrolled recursion in Sass::Parser::parsecssvariablevalue in parser.cpp).

MITRE

Affected Software

7 affected components
Sass-lang Libsass<=3.5.5
IBM Data Virtualization on Cloud Pak for Data<=3.0
IBM Watson Query on Cloud Pak for Data<=2.2
IBM Watson Query on Cloud Pak for Data<=2.1
IBM Watson Query on Cloud Pak for Data<=2.0
IBM Data Virtualization on Cloud Pak for Data<=1.8
IBM Data Virtualization on Cloud Pak for Data<=1.7

Event History

Apr 23, 2019
CVE Published
via MITRE·01:54 PM
Data Sourced
via MITRE·01:54 PM
Description
Aug 15, 2025
Data Sourced
via IBM·03:29 PM
DescriptionAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Free Weekly Intel

Don't miss critical vulnerabilities

Join thousands of security professionals who receive our weekly digest of trending CVEs, zero-days, and exploited vulnerabilities.

No spam. Unsubscribe anytime.

Frequently Asked Questions

1

What is CVE-2018-20821?

CVE-2018-20821 is a vulnerability in the parsing component of LibSass through version 3.5.5 that allows attackers to cause a denial-of-service through uncontrolled recursion.

2

What is the affected software?

The affected software is Sass-lang Libsass versions up to and including 3.5.5.

3

What is the severity of CVE-2018-20821?

The severity of CVE-2018-20821 is medium with a CVSS score of 6.5.

4

How can attackers exploit CVE-2018-20821?

Attackers can exploit CVE-2018-20821 by triggering uncontrolled recursion in the Sass::Parser::parse_css_variable_value function in parser.cpp.

5

Is there a fix for CVE-2018-20821?

Yes, upgrading to a version of LibSass beyond 3.5.5 will fix CVE-2018-20821.

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203