CVE-2026-9358

postcss-selector-parser AST Serialization container.js toString recursion

Published May 24, 2026 CVSS 4.0 · 5.3 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-w9m9-85wc-3x92 postcss-selector-parser allows denial of service through uncontrolled AST recursion
History
Type Values Removed Values 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)." 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.
Title postcss AST Serialization container.js toString recursion postcss-selector-parser AST Serialization container.js toString recursion
First Time appeared Postcss-selector-parser
Postcss-selector-parser postcss-selector-parser
CPEs cpe:2.3:a:postcss:postcss:*:*:*:*:*:*:*:* cpe:2.3:a:postcss-selector-parser:postcss-selector-parser:*:*:*:*:*:*:*:*
Vendors & Products Postcss-selector-parser
Postcss-selector-parser postcss-selector-parser
References
Metrics cvssV2_0

{'score': 5, 'vector': 'AV:N/AC:L/Au:N/C:N/I:N/A:P/E:POC/RL:ND/RC:C'}

cvssV3_0

{'score': 4.3, 'vector': 'CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L/E:P/RL:X/RC:C'}

cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L/E:P/RL:X/RC:C'}

cvssV2_0

{'score': 5, 'vector': 'AV:N/AC:L/Au:N/C:N/I:N/A:P/E:POC/RL:OF/RC:C'}

cvssV3_0

{'score': 4.3, 'vector': 'CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C'}

cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C'}

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values 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)."
Title postcss AST Serialization container.js toString recursion
First Time appeared Postcss
Postcss postcss
Weaknesses CWE-404
CWE-674
CPEs cpe:2.3:a:postcss:postcss:*:*:*:*:*:*:*:*
Vendors & Products Postcss
Postcss postcss
References
Metrics cvssV2_0

{'score': 5, 'vector': 'AV:N/AC:L/Au:N/C:N/I:N/A:P/E:POC/RL:ND/RC:C'}

cvssV3_0

{'score': 4.3, 'vector': 'CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L/E:P/RL:X/RC:C'}

cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L/E:P/RL:X/RC:C'}

cvssV4_0

{'score': 5.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulDB
Published
Updated
Jun 15, 2026, 7:21 AM
Reserved
May 23, 2026, 9:49 AM
Status
Deferred
Published
May 24, 2026, 6:16 AM
Modified
Jul 23, 2026, 11:10 AM