Private-network data exposure via permissive CORS default
Published Aug 18, 2024 · Updated Apr 7, 2025
Improper access control in Flask-CORS before 5.0.0 allows remote attackers to read private-network responses via crafted CORS requests. The default options in flask_cors/core.py set allow_private_network to true, causing qualifying preflight requests to receive Access-Control-Allow-Private-Network true. A victim browser must reach a Flask route using that default; successful exploitation exposes responses that browser private-network controls would otherwise block.
Summary
What happened
Improper access control in Flask-CORS before 5.0.0 allows remote attackers to read private-network responses via crafted CORS requests. The default options in flask_cors/core.py set allow_private_network to true, causing qualifying preflight requests to receive Access-Control-Allow-Private-Network true. A victim browser must reach a Flask route using that default; successful exploitation exposes responses that browser private-network controls would otherwise block.
The record
- CVE
- CVE-2024-6221
- Published
- Aug 18, 2024
- Updated
- Apr 7, 2025
- Vendor
- Cory Dolphin
- Product
- Flask-CORS
- Classifications
- CWE-284
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 18, 2024CVE publishedPublication date reported by the CVE source.
- Apr 7, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=4.0.1 <*
- Affected versionversion=unspecified <5.0.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo