The PHP engine attempts to read or execute the original pointer. Instead of processing the original variable, it executes the attacker's malicious data. Impact and Severity
The following vulnerabilities were patched in the transition to 5.6.40 or have been identified in the branch since its EOL: Heap-Based Buffer Overflows (CVE-2019-9023, CVE-2019-6977): Multiple issues in the
Known PHP exploit payloads (such as malicious EXIF metadata). Path traversal attempts. Remote file inclusion (RFI) attacks. 4. Harden the php.ini Configuration
On February 13, 2020, the PHP development team released PHP version 5.6.40, which is a security release that fixes several vulnerabilities. These vulnerabilities were reported by security researchers and developers, and they have been verified by the PHP team. The vulnerabilities fixed in PHP 5.6.40 include: php version 5640 vulnerabilities verified
Since January 2019, any newly discovered vulnerability affecting the core architecture of PHP 5.6 remains unpatched by the open-source community. Threat actors actively look for servers running PHP 5.6.40 because they know public exploits will never face an official core patch. Modern CMS Incompatibility
A Use-After-Free vulnerability happens when a program continues to use a pointer after the memory it references has been deallocated (freed). In the context of PHP 5.6.40:
As of March 2026, only four PHP versions are actively supported: 8.2, 8.3, 8.4, and 8.5. Everything from PHP 8.1 and below is end- FreePBX 15.0.17.67 PHP Version 5.6.40 vulnerability The PHP engine attempts to read or execute
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Verification & Assessment (ongoing)
This vulnerability was found in the sapi_read_post_data function within the CLI SAPI interface. It is a use-after-free vulnerability that could allow a remote attacker to pass specially crafted responses to the application, potentially leading to arbitrary code execution on the system. Path traversal attempts
If you meant a different version number (e.g., 5.6.40 is clear, but “5640” could be a typo for 5.4.40, 7.4.0, or 8.4.0), please clarify — I can provide the exact CVE list for that version as well.
⚠️ Automated exploit kits specifically target PHP 5.6 due to its widespread legacy use and lack of official patches.