| CVE | Description | Impact | |------|-------------|--------| | | FastCGI (PHP-FPM) — specially crafted request causes 502 response and memory corruption | Remote Code Execution (RCE) under certain configurations | | CVE-2019-9641 | exif_read_data() — heap-based buffer over-read | Information disclosure / DoS | | CVE-2019-9021 | php_url_parse_ex() — invalid URL parsing leads to CRLF injection | HTTP response splitting, SSRF | | CVE-2019-9020 | xmlrpc_decode() — persistent use-after-free | RCE (theoretical, DoS confirmed) | | CVE-2016-1903 | imap_open() — improper argument filtering | RCE via mailbox name parameter (still present in 5.6.40) |
If you absolutely cannot upgrade your code, switch from standard vanilla PHP 5.6.40 to a commercial or community repository that backports security fixes:
This write-up provides a verified security analysis of PHP 5.6.40 , which was the final release of the 5.6 branch. Status Summary Release Date: January 10, 2019 End-of-Life (EOL):
If a hacker controls a string input and you compare it to a hash or a number, PHP 5 might convert it unexpectedly.
: Invalid input passed to the xmlrpc_decode() function triggers an invalid memory access flaw (heap out-of-bounds read or use-after-free). php version 5640 vulnerabilities verified
Threat actors use automated scanners specifically looking for the X-Powered-By: PHP/5.6.40 HTTP header to launch instant, automated exploits. Remediation and Mitigation Strategies
[ Automated Scanner ] ──> Finds PHP 5.6.40 Header ──> [ Exploit Delivery (EXIF/Unserialize) ] ──> [ Web Shell Installed ]
Do you need help in your application that might break during an upgrade to PHP 8?
When a vulnerability scanner flags PHP 5.6.40, it is verifying the existence of several specific memory corruption and input validation flaws. According to the official PHP ChangeLog , the core subsystems affected include: 1. Multibyte String Flaws (CVE-2019-9023) According to the official PHP ChangeLog , the
Vulnerabilities in PHP's core handling of memory allocation can lead to system crashes or memory corruption.
Under frameworks like GDPR, HIPAA, or CCPA, failing to secure user data using up-to-date, industry-standard technology leaves your company liable for massive negligence lawsuits if a breach occurs.
within the GD library, allowing for unspecified impact via crafted image data. XML-RPC Vulnerabilities CVE-2019-9020 & CVE-2019-9024 : These involve heap out-of-bounds reads in the xmlrpc_decode
Attackers can exploit these memory flaws to crash the web server (Denial of Service) or bypass security mechanisms to read restricted memory sectors. 3. OpenSSL Extension Vulnerabilities PHP 5.6.40 compiles against older cryptographic standards. within the GD library
(an OS command injection vulnerability with a CVSS score of 9.8)—officially affect all EOL versions, including PHP 5.6.40. Attackers frequently use these unpatched RCE (Remote Code Execution) flaws to deploy: Web shells for persistent server access. Cryptominers and DDoS botnet malware. Data exfiltration tools for sensitive database access. Strategic Recommendations PHP 5.6.x < 5.6.40 Multiple vulnerabilities. | Tenable® 26 May 2025 —
If your business logic completely prevents an immediate upgrade, you must source patches from third-party vendors who provide extended commercial support for EOL software.
Specially crafted files (like a corrupted JPEG image parsed via EXIF) can trigger a buffer overflow.