CVE-2018-20821
MEDIUMEPSS 82th pctlDescription
The parsing component in LibSass through 3.5.5 allows attackers to cause a denial-of-service (uncontrolled recursion in Sass::Parser::parse_css_variable_value in parser.cpp).
How to fix
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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Exploit Intelligence
Elevated risk: more likely to be exploited than 82% of all known CVEs.
References
Related Vulnerabilities
Other CWE-674 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2021-45105 | Medium | 5.9 | 100% | - | Fix |
| CVE-2024-25111 | High | 8.6 | 65% | - | Fix |
| CVE-2023-50269 | High | 8.6 | 58% | - | Fix |
| CVE-2021-42697 | High | 7.5 | 36% | - | Fix |
| CVE-2018-0739 | Medium | 6.5 | 19% | - | Fix |
| CVE-2007-1285 | High | 7.5 | 18% | - | Fix |
Common questions
How do I fix CVE-2018-20821?
Upgrade libsass on debian 12 to 3.6.3-1 or later.
Is CVE-2018-20821 being actively exploited?
Not that we know of. CVE-2018-20821 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 2.2% is the estimated probability that it will be exploited in the next 30 days. That is higher than 82% of all scored CVEs.
How severe is CVE-2018-20821?
CVE-2018-20821 has a CVSS v3 base score of 6.5, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2018-20821 affect?
Published advisories record a fix for libsass (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-17.