CVE-2026-9358
postcss AST Serialization container.js toString recursion
Description
A vulnerability was determined in postcss up to 7.1.1. 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. 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)."
INFO
Published Date :
May 24, 2026, 6:16 a.m.
Last Modified :
May 26, 2026, 7:54 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 2.0 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | LOW | [email protected] |
Solution
- Update PostCSS to the latest version.
- Review CSS compilation for uncontrolled recursion.
- Apply vendor mitigation if compilation is user-driven.
- Monitor for potential exploits in user-generated CSS.
Public PoC/Exploit Available at Github
CVE-2026-9358 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-9358.
| URL | Resource |
|---|---|
| https://gist.github.com/bx33661/581e3a38134601c04e19b4dfc9b459b9 | |
| https://vuldb.com/submit/813080 | |
| https://vuldb.com/vuln/365321 | |
| https://vuldb.com/vuln/365321/cti |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-9358 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-9358
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
A CSS selector parser, integrates with postcss but does not require it.
JavaScript TypeScript
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-9358 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-9358 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
May. 24, 2026
Action Type Old Value New Value Added Description A vulnerability was determined in postcss up to 7.1.1. 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. 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)." Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L Added CVSS V2 (AV:N/AC:L/Au:N/C:N/I:N/A:P) Added CWE CWE-404 Added CWE CWE-674 Added Reference https://gist.github.com/bx33661/581e3a38134601c04e19b4dfc9b459b9 Added Reference https://vuldb.com/submit/813080 Added Reference https://vuldb.com/vuln/365321 Added Reference https://vuldb.com/vuln/365321/cti