CVE-2026-41305Public exploitNetwork attack vector

Cross-site scripting via unescaped style-tag closure

Published Apr 24, 2026 · Updated Apr 24, 2026

Cross-site scripting in PostCSS before 8.5.10 allows remote attackers to execute script in a user's browser via crafted CSS input. The CSS AST stringifier emits attacker-controlled closing style-tag sequences unchanged, so HTML embedding ends the style element and interprets the remainder as markup. Exploitation requires an application to accept untrusted CSS, stringify it with PostCSS, embed the result in an HTML style element, and have a user load that page.

CVSS severity6.1
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in PostCSS before 8.5.10 allows remote attackers to execute script in a user's browser via crafted CSS input. The CSS AST stringifier emits attacker-controlled closing style-tag sequences unchanged, so HTML embedding ends the style element and interprets the remainder as markup. Exploitation requires an application to accept untrusted CSS, stringify it with PostCSS, embed the result in an HTML style element, and have a user load that page.

The record

CVE
CVE-2026-41305
Published
Apr 24, 2026
Updated
Apr 24, 2026
Vendor
PostCSS
Product
PostCSS
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 8.5.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PostCSS · PostCSSversion=< 8.5.10

Published CVSS scores

6.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript/JScript

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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