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Sabberworm PHP CSS Parser Code injection vulnerability in allSelectors()

Critical severity GitHub Reviewed Published Mar 26, 2022 to the GitHub Advisory Database • Updated Nov 3, 2025

Package

composer sabberworm/php-css-parser (Composer)

Affected versions

>= 8.3.0, < 8.3.1
>= 8.2.0, < 8.2.1
>= 8.1.0, < 8.1.1
>= 8.0.0, < 8.0.1
>= 7.0.0, < 7.0.4
>= 6.0.0, < 6.0.2
>= 5.2.0, < 5.2.1
>= 5.1.0, < 5.1.3
>= 5.0.0, < 5.0.9
>= 4.0.0, < 4.0.1
>= 3.0.0, < 3.0.1
>= 2.0.0, < 2.0.1
>= 1.0.0, < 1.0.1

Patched versions

8.3.1
8.2.1
8.1.1
8.0.1
7.0.4
6.0.2
5.2.1
5.1.3
5.0.9
4.0.1
3.0.1
2.0.1
1.0.1

Description

Sabberworm PHP CSS Parser before 8.3.1 calls eval on uncontrolled data, possibly leading to remote code execution if the function allSelectors() or getSelectorsBySpecificity() is called with input from an attacker.

References

Published by the National Vulnerability Database Jun 3, 2020
Published to the GitHub Advisory Database Mar 26, 2022
Reviewed Mar 26, 2022
Last updated Nov 3, 2025

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(96th percentile)

Weaknesses

Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Learn more on MITRE.

Improper Control of Generation of Code ('Code Injection')

The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. Learn more on MITRE.

CVE ID

CVE-2020-13756

GHSA ID

GHSA-phrq-v4q2-hmq6

Source code

No known source code
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