CVE-2026-9358 Details
Description
A vulnerability was determined in postcss-selector-parser up to 6.1.2/7.1.2. Affected is the function toString of the file src/selectors/container.js of the component AST Serialization. Executing a manipulation can lead to uncontrolled recursion. It is possible to launch the attack remotely. The exploit has been publicly disclosed and may be utilized. Upgrading to version 6.1.3 and 7.1.3 is able to address this issue. This patch is called 5bc698cef66f8abd12610dc623e5d67cbc0f869d. It is suggested to upgrade the affected component. The vendor explains, that according to his definition "DoS on server-side on user-generated CSS is low risk for us (since most users compile own CSS with PostCSS)." The commits were backported to 6.x branch, which was the most downloaded version.
A denial-of-service vulnerability has been identified in PostCSS versions through 7.1.1. The issue arises in the AST serialization process, specifically within the 'toString' function of 'src/selectors/container.js'. This vulnerability allows for uncontrolled recursion, which can be exploited remotely. When the 'toString' method is called on deeply nested pseudo-class trees, it can lead to a stack overflow, causing the application to crash. The vulnerability is accessible through the PostCSS plugin ecosystem and can be triggered by supplying a malicious CSS file or by programmatically constructing a deep AST using the PostCSS selector parser.
Users can upgrade to PostCSS versions 8.0.0 and above, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed May 24, 2026CISA-ADP
Assessed May 29, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://gist.github.com/bx33661/581e3a38134601c04e19b4dfc9b459b9 | [email protected] | ExploitTechnical Analysis |
| https://github.com/postcss/postcss-selector-parser/commit/5bc698cef66f8abd12610dc623e5d67cbc0f869d | [email protected] | |
| https://github.com/postcss/postcss-selector-parser/releases/tag/7.1.3 | [email protected] | |
| https://vuldb.com/cve/CVE-2026-9358 | [email protected] | |
| https://vuldb.com/submit/813080 | [email protected] | Permission Required |
| https://vuldb.com/vuln/365321 | [email protected] | AdvisoryPermission Required |
| https://vuldb.com/vuln/365321/cti | [email protected] | AdvisoryPermission Required |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-404 | Improper Resource Shutdown or Release | [email protected] |
| CWE-674 | Uncontrolled Recursion | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| postcss-selector-parser | <= 7.1.1 (semver) |
CPE
Remediation
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Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 23, 2026 | CVE Translated | [email protected] |
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Jun 15, 2026 | CVE Modified | [email protected] |
| May 24, 2026 | New CVE Received | [email protected] |