CVE-2023-44270Public exploitNetwork attack vector

CSS validation bypass via carriage-return misparsing

Published Sep 29, 2023 · Updated Nov 3, 2025

Injection in PostCSS before 8.4.31 allows remote attackers to bypass CSS validation via crafted CSS containing a carriage return. The tokenizer's RE_BAD_BRACKET expression omits carriage returns, so a return before a comment opener causes browser-visible text to be represented incorrectly in PostCSS output nodes. Exposure requires a linter or validator that parses external untrusted CSS; ordinary build-time processing without attacker-controlled CSS does not expose this path.

CVSS severity5.3
Medium
EPSS probability0.82%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Injection in PostCSS before 8.4.31 allows remote attackers to bypass CSS validation via crafted CSS containing a carriage return. The tokenizer's RE_BAD_BRACKET expression omits carriage returns, so a return before a comment opener causes browser-visible text to be represented incorrectly in PostCSS output nodes. Exposure requires a linter or validator that parses external untrusted CSS; ordinary build-time processing without attacker-controlled CSS does not expose this path.

The record

CVE
CVE-2023-44270
Published
Sep 29, 2023
Updated
Nov 3, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-144, CWE-74
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 29, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.3GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-144Improper Neutralization of Line Delimiters
CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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