Ubuntu fixes pecl_http type confusion: remote code execution possible

Ubuntu has published security notice USN-9055-1 addressing a vulnerability in pecl_http, the PHP HTTP extension. The flaw stems from incorrect handling of certain HTTP request parameters that leads to type confusion, a memory safety defect where an object is accessed as an incompatible type. A remote attacker exploiting this weakness could trigger a PHP crash causing denial of service, or potentially achieve arbitrary code execution within the PHP process. The vulnerability affects systems running pecl_http on Ubuntu, with the security team releasing patched packages to close the attack vector.

The defect class is type confusion, a common source of memory corruption in applications written in C and C++ such as PHP and its extensions. The attack vector is remote and does not require authentication, making internet-facing PHP applications using pecl_http particularly exposed. Administrators should apply the updated packages promptly, especially for production web servers handling untrusted HTTP requests.

Vulnerability details and affected systems

• CVE and defect class: The vulnerability is a type confusion in pecl_http, a C-based PHP extension, where HTTP request parameters are processed with incorrect type assumptions leading to memory corruption.
• Attack vector: Remote and unauthenticated; any attacker capable of sending HTTP requests to a vulnerable application can trigger the flaw.
• Impact scope: Successful exploitation can cause PHP to crash (denial of service) or potentially lead to arbitrary code execution within the PHP interpreter's security context.
• Affected component: The pecl_http PHP extension specifically, not PHP core; systems with this extension installed and enabled are at risk.
• Remediation: Ubuntu has issued patched packages through standard security channels; the fix corrects parameter handling to prevent type confusion.

Why it matters

PHP remains a cornerstone of web infrastructure powering millions of sites, and pecl_http is widely used for advanced HTTP client functionality in PHP applications. This vulnerability is particularly significant for shared hosting environments and cloud deployments where PHP processes run with privileges that could amplify the impact of arbitrary code execution. The remote, unauthenticated nature of the flaw places it in a critical remediation priority for system administrators maintaining Ubuntu LTS servers with exposed web applications.