CVE-2026-9358: Uncontrolled Recursion in postcss-selector-parser
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.
AI Analysis
Technical Summary
CVE-2026-9358 is a medium severity vulnerability in the postcss-selector-parser component affecting the toString function in src/selectors/container.js. The flaw allows an attacker to cause uncontrolled recursion, potentially leading to a denial of service. This can be exploited remotely by manipulating user input. The vulnerability affects versions 6.1.0 through 6.1.2 and 7.1.0 through 7.1.2. The issue has been fixed in versions 6.1.3 and 7.1.3 by a patch identified as 5bc698cef66f8abd12610dc623e5d67cbc0f869d. The vendor notes the risk is low due to typical usage patterns where users compile their own CSS.
Potential Impact
An attacker can remotely trigger uncontrolled recursion in the toString function, causing a denial of service condition on the server processing user-generated CSS. The impact is limited to availability degradation. There is no indication of code execution or data breach. The CVSS 4.0 base score is 5.3 (medium severity), reflecting network attack vector, low complexity, no privileges required, and low impact on availability.
Mitigation Recommendations
A fix is available by upgrading postcss-selector-parser to versions 6.1.3 or 7.1.3. Users should apply these updates to remediate the vulnerability. The vendor considers the risk low and notes that most users compile their own CSS, which may reduce exposure. No additional mitigations are specified.
CVE-2026-9358: Uncontrolled Recursion in postcss-selector-parser
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.
CVSS v4.0
Score 5.3medium
Affected software
pkg:npm/postcss-selector-parserRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-9358 is a medium severity vulnerability in the postcss-selector-parser component affecting the toString function in src/selectors/container.js. The flaw allows an attacker to cause uncontrolled recursion, potentially leading to a denial of service. This can be exploited remotely by manipulating user input. The vulnerability affects versions 6.1.0 through 6.1.2 and 7.1.0 through 7.1.2. The issue has been fixed in versions 6.1.3 and 7.1.3 by a patch identified as 5bc698cef66f8abd12610dc623e5d67cbc0f869d. The vendor notes the risk is low due to typical usage patterns where users compile their own CSS.
Potential Impact
An attacker can remotely trigger uncontrolled recursion in the toString function, causing a denial of service condition on the server processing user-generated CSS. The impact is limited to availability degradation. There is no indication of code execution or data breach. The CVSS 4.0 base score is 5.3 (medium severity), reflecting network attack vector, low complexity, no privileges required, and low impact on availability.
Mitigation Recommendations
A fix is available by upgrading postcss-selector-parser to versions 6.1.3 or 7.1.3. Users should apply these updates to remediate the vulnerability. The vendor considers the risk low and notes that most users compile their own CSS, which may reduce exposure. No additional mitigations are specified.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulDB
- Date Reserved
- 2026-05-23T09:49:26.559Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a1297c609f6977edb24a74b
Added to database: 05/24/2026, 06:16:38 UTC
Last enriched: 06/15/2026, 09:05:01 UTC
Last updated: 07/31/2026, 19:23:00 UTC
Views: 100
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