CVE-2021-32708
9.8 · CRITICALOverview
CVE-2021-32708 is a critical-severity vulnerability affecting thephpleague flysystem. It was published on June 24, 2021 and has a CVSS 3.1 base score of 9.8 (CRITICAL).
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
Flysystem is an open source file storage library for PHP. The whitespace normalisation using in 1.x and 2.x removes any unicode whitespace. Under certain specific conditions this could potentially allow a malicious user to execute code remotely. The conditions are: A user is allowed to supply the path or filename of an uploaded file, the supplied path or filename is not checked against unicode chars, the supplied pathname checked against an extension deny-list, not an allow-list, the supplied path or filename contains a unicode whitespace char in the extension, the uploaded file is stored in a directory that allows PHP code to be executed. Given these conditions are met a user can upload and execute arbitrary code on the system under attack. The unicode whitespace removal has been replaced with a rejection (exception). For 1.x users, upgrade to 1.1.4. For 2.x users, upgrade to 2.1.1.
Remediation
Check the references section for vendor advisories and patches from thephpleague. Update flysystem to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| thephpleague | flysystem | >= 1.0.0, < 1.1.4 | Affected |
References
Frequently Asked Questions
What is CVE-2021-32708?
CVE-2021-32708 is a critical-severity vulnerability affecting thephpleague flysystem. It was published on June 24, 2021 and has a CVSS 3.1 base score of 9.8 (CRITICAL).
How severe is CVE-2021-32708?
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-32708?
Check the references section for vendor advisories and patches from thephpleague. Update flysystem to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-32708?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-32708 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
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Browser-based exploitation validates findings with real proof-of-concept.
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