Authenticated code execution via attachment extension bypass
Published Jun 24, 2020 · Updated Aug 4, 2024
Unrestricted file upload in ExpressionEngine before 5.3.2 allows remote authenticated users to execute arbitrary PHP code via message attachments. The legacy Upload library checks a percent-20-suffixed .php filename against its extension blacklist before clean_file_name normalizes it, while a valid PNG MIME type passes the allowlist and the attachment remains web-accessible. Member access with permission to compose messages is sufficient, and executing the stored attachment compromises the web application under the PHP process account.
Summary
What happened
Unrestricted file upload in ExpressionEngine before 5.3.2 allows remote authenticated users to execute arbitrary PHP code via message attachments. The legacy Upload library checks a percent-20-suffixed .php filename against its extension blacklist before clean_file_name normalizes it, while a valid PNG MIME type passes the allowlist and the attachment remains web-accessible. Member access with permission to compose messages is sufficient, and executing the stored attachment compromises the web application under the PHP process account.
The record
- CVE
- CVE-2020-13443
- Published
- Jun 24, 2020
- Updated
- Aug 4, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-434, T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jun 24, 2020CVE publishedPublication date reported by the CVE source.
- Aug 4, 2024Record 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?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
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
- CVE-2020-13443 message-attachment proof of conceptproof of concept · demonstrated
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