CVE-2026-41305 | PostCSS has XSS via Unescaped </style> in its CSS Stringify Output

PostCSS takes a CSS file and provides an API to analyze and modify its rules by transforming the rules into an Abstract Syntax Tree. Versions prior to 8.5.10 do not escape `</style>` sequences when stringifying CSS ASTs. When user-submitted CSS is parsed and re-stringified for embedding in HTML `<style>` tags, `</style>` in CSS values breaks out of the style context, enabling XSS. Version 8.5.10 fixes the issue.

Published: 2026-04-24 Last update: 2026-04-24 Assigner: [email protected] Source: [email protected]
NVD Status：Deferred，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-41305 is rated Low Risk (27.3/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.03%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-41305

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-24 — 0.03% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-41305

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.1 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 2.7 [email protected]

Weakness enumeration for CVE-2026-41305

GitHub Security Advisory for CVE-2026-41305

GHSA-qx2v-qp2m-jg93 · Severity: medium · Ecosystem: npm — PostCSS has XSS via Unescaped </style> in its CSS Stringify Output

OS Trackers for CVE-2026-41305

vendor priority summary link
debian not yet assigned CVE-2026-41305 not yet assigned priority: Debian including 1 source packages (node-postcss), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-41305
redhat medium — https://access.redhat.com/security/cve/CVE-2026-41305
ubuntu medium CVE-2026-41305 medium priority: Ubuntu including 1 source packages (node-postcss), 6 status rows across 6 suites (focal, jammy, noble, questing, resolute, upstream): needs-triage 6. https://ubuntu.com/security/CVE-2026-41305

Affected software / configurations for CVE-2026-41305

Vendor Product Version Raw CPE
No affected products in dataset.

References for CVE-2026-41305

cvelogic Threat Intelligence