CVE-2023-44270: Postcss PostCSS Line Return Parsing Error Vulnerability

MODERATE
Advisory Identifier: GHSA-7fh5-64p2-3v2j
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CVSS 5.3
CWE-144 CWE-74
Published
Advisory Summary

CVE-2023-44270 is a MODERATE (CVSS 5.3) postcss line return parsing error vulnerability (CWE-144: Improper Neutralization of Line Delimiters) affecting Postcss libraries in the npm ecosystem. The issue involves postcss line return parsing error. Remediation is available by upgrading affected packages to version 8.4.31.

CVE-2023-44270 at a Glance

CVE Identifier CVE-2023-44270
GHSA Identifier GHSA-7fh5-64p2-3v2j
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-144: Improper Neutralization of Line Delimiters
Affected Product Postcss
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2023-44270

To remediate this vulnerability, upgrade all affected Postcss dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

postcss fixed: 8.4.31 
npm install postcss@8.4.31
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls postcss

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2023-44270, inspect your project dependencies using npm:

npm ls postcss

Analyze the terminal output to locate any version of Postcss in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 8.4.31), your application is affected.

Note: The npm ls postcss command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-144: Improper Neutralization of Line Delimiters, where the product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as line delimiters when they are sent to a downstream component. In Postcss, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

An issue was discovered in PostCSS before 8.4.31. It affects linters using PostCSS to parse external Cascading Style Sheets (CSS). There may be `\r` discrepancies, as demonstrated by `@font-face{ font:(\r/*);}` in a rule. This vulnerability affects linters using PostCSS to parse external untrusted CSS. An attacker can prepare CSS in such a way that it will contains parts parsed by PostCSS as a CSS comment. After processing by PostCSS, it will be included in the PostCSS output in CSS nodes (rules, properties) despite being originally included in a comment.

CVE-2023-44270 Affected Postcss Versions

1 component(s)
Fixed Versions:
8.4.31
Product / Package Ecosystem Affected Versions Fixed Version
postcss
npm/postcss
npm
< 8.4.31
8.4.31

References

NVD — CVE-2023-44270 NVD
https://nvd.nist.gov/vuln/detail/CVE-2023-44270
Postcss Source Repository REPOSITORY
https://github.com/github/advisory-database/issues/2820
Security Fix Commit FIX COMMIT
https://github.com/postcss/postcss/commit/58cc860b4c1707510c9cd1bc1fa30b423a9ad6c5
Postcss Source Repository REPOSITORY
https://github.com/postcss/postcss
Postcss Source Repository REPOSITORY
https://github.com/postcss/postcss/blob/main/lib/tokenize.js#L25
Postcss Release RELEASE
https://github.com/postcss/postcss/releases/tag/8.4.31
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2024/12/msg00025.html

Frequently Asked Questions

What is CVE-2023-44270?
CVE-2023-44270 is a security vulnerability in Postcss involving PostCSS line return parsing error under CWE-144: Improper Neutralization of Line Delimiters.
Which Postcss versions are affected?
Affected versions include releases prior to 8.4.31 across affected packages: postcss.
What version fixes CVE-2023-44270?
Upgrading to 8.4.31 (or the latest patched release for your respective branch) resolves the vulnerability.
Is postcss affected?
Yes, postcss is affected in releases prior to 8.4.31. Upgrade your dependency to 8.4.31 or later.
What is the CVSS score of CVE-2023-44270?
CVE-2023-44270 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2023-44270?
CVE-2023-44270 is classified under CWE-144: Improper Neutralization of Line Delimiters (The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as line delimiters when they are sent to a downstream component.).
How can I check npm dependencies for CVE-2023-44270?
Run the dependency tree command: 'npm ls postcss'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-7fh5-64p2-3v2j",
  "modified" : "2025-11-04T16:45:01Z",
  "published" : "2023-09-30T00:31:10Z",
  "aliases" : [ "CVE-2023-44270" ],
  "summary" : "PostCSS line return parsing error",
  "details" : "An issue was discovered in PostCSS before 8.4.31. It affects linters using PostCSS to parse external Cascading Style Sheets (CSS). There may be `\\r` discrepancies, as demonstrated by `@font-face{ font:(\\r/*);}` in a rule.\n\nThis vulnerability affects linters using PostCSS to parse external untrusted CSS. An attacker can prepare CSS in such a way that it will contains parts parsed by PostCSS as a CSS comment. After processing by PostCSS, it will be included in the PostCSS output in CSS nodes (rules, properties) despite being originally included in a comment.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "postcss"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "8.4.31"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2023-44270"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/github/advisory-database/issues/2820"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/postcss/postcss/commit/58cc860b4c1707510c9cd1bc1fa30b423a9ad6c5"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/postcss/postcss"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/postcss/postcss/blob/main/lib/tokenize.js#L25"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/postcss/postcss/releases/tag/8.4.31"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2024/12/msg00025.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-144", "CWE-74" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-10-03T15:04:58Z",
    "nvd_published_at" : "2023-09-29T22:15:11Z"
  }
}