PT-2021-21939 · Nth-Check+3 · Nth-Check+3

Published 2021-09-17 · Updated 2025-12-03 · CVE-2021-3803

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions: nth-check versions (affected versions not specified)

Description: The issue is related to Inefficient Regular Expression Complexity, specifically a Regular Expression Denial of Service (ReDoS) vulnerability. This vulnerability causes a denial of service when parsing crafted invalid CSS nth-checks. The ReDoS vulnerability is mainly due to the sub-pattern s*(?:([+-]?)s*(d+))? with quantified overlapping adjacency.

Recommendations: At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Exploit

DoS

Weakness Enumeration

CWE-1333

Related Identifiers

CVE-2021-3803

DLA-3428-1

GHSA-RP65-9CF3-CJXR

USN-6114-1

Affected Products

Bitbucket

Linuxmint

Ubuntu

Nth-Check

References · 24

• 🔥 https://huntr.dev/bounties/8cf8cc06-d2cf-4b4e-b42c-99fafb0b04d0 · Exploit
• https://github.com/fb55/nth-check/commit/9894c1d2010870c351f66c6f6efcf656e26bb726 · Patch
• https://ubuntu.com/security/notices/USN-6114-1 · Vendor Advisory
• https://osv.dev/vulnerability/ROOT-APP-NPM-CVE-2021-3803 · Vendor Advisory
• http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3803 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2021-3803 · Security Note
• https://osv.dev/vulnerability/USN-6114-1 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-3803 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2021-3803 · Security Note
• https://security-tracker.debian.org/tracker/CVE-2021-3803 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2021-3803 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-rp65-9cf3-cjxr · Vendor Advisory
• https://osv.dev/vulnerability/UBUNTU-CVE-2021-3803 · Vendor Advisory
• https://osv.dev/vulnerability/DLA-3428-1 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2021-3803 · Vendor Advisory