CVE-2026-128014 in FrankenPHP
Summary
by MITRE • 11/13/2026
FrankenPHP standalone static binaries 1.8.0 before 1.13.2 bundle the PHP brotli extension statically linked with Brotli 1.2.0, whose decoder contains an out-of-bounds write (CVE-2026-111497). Unauthenticated remote attackers can send crafted data to applications that pass it to brotli_uncompress_add() to crash the entire FrankenPHP process, and possibly cause memory disclosure or code execution.
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Analysis
by VulDB Data Team • 11/13/2026
The vulnerability identified as CVE-2026-111497 represents a critical security flaw within the static binaries of FrankenPHP versions 1.8.0 through 1.13.2. This issue stems from the bundling of the PHP brotli extension, which is statically linked against version 1.2.0 of the Brotli compression library. The core technical defect lies in an out-of-bounds write condition present within the decoder component of this specific Brotli release. When applications utilizing these FrankenPHP binaries process compressed data via the brotli_uncompress_add() function, they invoke the vulnerable decoding routine without adequate bounds checking or input validation mechanisms to prevent memory corruption.
From a technical perspective, an out-of-bounds write allows malicious actors to overwrite adjacent memory locations with crafted input data. This type of memory safety violation is classified under CWE-787: Out-of-Bounds Write in standard vulnerability taxonomies. The severity of this flaw is amplified by its potential for exploitation without authentication. An unauthenticated remote attacker can interact directly with the application interface, sending specially constructed compressed payloads that trigger the buffer overflow during decompression. Because FrankenPHP operates as a high-performance web server and PHP runtime environment, crashing the process disrupts service availability for all users connected to that instance.
The operational impact of this vulnerability extends beyond simple denial of service. While an immediate crash results in a Denial of Service (DoS), the underlying memory corruption opens pathways for more severe attacks. Depending on the specific memory layout and execution context, an attacker may achieve arbitrary code execution or sensitive information disclosure through heap spraying techniques or by overwriting critical function pointers. This aligns with ATT&CK technique T1059: Command and Scripting Interpreter if script injection is possible, or T1203: Exploitation for Client Execution in broader contexts where the server acts as a gateway to backend systems. The static linking of the vulnerable library means that updating individual components within a dynamic environment is not feasible; instead, users must rely on vendor-provided patches that replace the entire binary with one containing an updated Brotli version or patched extension code.
Mitigation strategies require immediate action by system administrators and developers using affected versions. The primary remediation step is to upgrade FrankenPHP to version 1.13.2 or later, where this vulnerability has been addressed in the bundled libraries. For environments unable to update immediately due to compatibility constraints, implementing strict input validation at the application layer can help mitigate risk by filtering out malformed compressed data before it reaches the brotli_uncompress_add() function. Additionally, deploying Web Application Firewalls with deep packet inspection capabilities may detect and block anomalous compression patterns associated with this exploit vector. Regular security audits and dependency management practices are essential to prevent similar issues arising from bundled third-party libraries in future releases.