Topic
CVE-2026-109618
PHP2Shell Vulnerabilities Enable Pre-Application Code Execution on Unpatched Servers
Vulnerabilities & ExploitsPHP2Shell Campaign Chains PHP and Linux Kernel Flaws to Compromise 25 Servers Including US Government-Linked Network
Vulnerabilities & Exploits
PHP Patched Against PHP2Shell: Save php -v Output as Potential Court Evidence
Vulnerabilities & ExploitsCISA Adds PHP2Shell Flaws CVE-2026-109618 and CVE-2026-109619 to KEV Catalog After Confirmed Exploitation
The U.S. Cybersecurity and Infrastructure Security Agency has confirmed active exploitation of two remotely exploitable vulnerabilities in PHP collectively known as PHP2Shell. CVE-2026-109618 stems from improper handling during memory exhaustion, while CVE-2026-109619 involves use-after-free issues in internal state management. Both flaws allow unauthenticated remote code execution and pose elevated risk to any PHP environment processing external requests such as web servers. PHP development teams released patches on October 21 for supported branches including PHP 8.5.12, 8.4.27, 8.3.36 and 8.2.35, along with source-level fixes for end-of-life versions 7.4, 8.0 and 8.1. CISA has set a three-day remediation deadline of October 29 for U.S. federal agencies and requires verification that systems have not been compromised.
Security Week 2644: Active Exploitation of PHP2Shell Vulnerabilities Confirmed
PHP developers released patches for two critical vulnerabilities collectively known as PHP2Shell on October 20, affecting PHP 8.2 through 8.5 as well as older branches. The flaws allow unauthenticated remote code execution on affected servers, which power approximately 70 percent of websites. Despite expectations of immediate exploitation, confirmed attacks with working exploits only began on October 25. CrowdStrike noted technical difficulties in weaponizing the issues in real-world environments. Only one-fifth of top Russian websites had applied the fixes by October 25. Additional incidents included compromised eMudhra certificates, a critical GitLab flaw, and a 16-year-old Broadcom router vulnerability.
Critical Code Injection Flaw in Okta Access Gateway Allows Authenticated Command Execution
Okta disclosed CVE-2026-115547, a critical code injection vulnerability in the administrative console of Okta Access Gateway. An authenticated administrator can execute arbitrary commands on the underlying system using the privileges of the gateway service account. The flaw received a CVSS 3.1 score of 9.1 and stems from insufficient input validation when processing configuration values in a specific format. Affected appliances running versions prior to 2026.10.2 must be updated, as no workaround is provided. The same disclosure day also included CVE-2026-115546 for authentication source verification and two PHP execution issues (CVE-2026-109618, CVE-2026-109619) previously seen in Palo Alto PAN-OS. Exploitation requires administrative console access and no in-the-wild attacks have been reported.
Critical PHP Vulnerabilities CVE-2026-109618 and CVE-2026-109619 Enable Unauthenticated Remote Code Execution
Two critical vulnerabilities in PHP, tracked as CVE-2026-109618 and CVE-2026-109619, both scoring CVSS 9.2, were disclosed on October 21. The flaws allow attackers to execute arbitrary code without authentication by triggering out-of-memory conditions that lead to use-after-free memory corruption. Exploitation involves specially crafted requests that manipulate uninitialized arrays and function pointers, with full chains demonstrated via PHP_SESSION_UPLOAD_PROGRESS and fatal error backtraces. The issues affect PHP versions starting from 5.4 and were discovered using AI tools Gemini 4 Argon and GPT-5.6 Sol, resulting in a patch exceeding 10,000 lines of code. Amazon detected attacks as early as October 17, with Cloudflare later reporting millions of exploitation attempts. Mitigation requires updating to patched versions such as PHP 8.2.35, 8.3.36, 8.4.27 or 8.5.12, while temporary workarounds include disabling session upload progress and fatal error backtraces.
Mitigating PHP2Shell RCE Vulnerabilities CVE-2026-109618 and CVE-2026-109619 on Legacy PHP 5.6 Stacks with Varnish, Docker and Apache mod_php
Two critical remote code execution vulnerabilities dubbed PHP2Shell (CVE-2026-109618 and CVE-2026-109619, CVSS 9.2) affect PHP before any application code executes, targeting the Zend Engine's longjmp() mechanism during OOM conditions and use-after-free issues with session upload progress. Official patches exist only for supported branches 8.2.35 and newer, leaving PHP 5.6 installations exposed, especially those using Apache with mod_php. An administrator of a high-traffic legacy enterprise application running PHP 5.6 inside Docker containers behind Varnish implemented a four-layer defense without rewriting the monolith. The approach disables session.upload_progress.enabled and sets memory_limit to -1 inside PHP, enforces strict cgroups memory limits and MaxConnectionsPerChild 1 in Apache, adds request-size and cookie-based blocks in Varnish VCL, and forces Connection: close on synthetic error responses. Testing revealed HTTP keep-alive drain issues and differing behavior between direct Apache requests and Varnish-routed traffic. The layered controls successfully neutralize both attack vectors while preserving production stability.
PHP Foundation Reveals Two Critical RCE Vulnerabilities Fixed After 2024 Discovery Delays
The PHP Foundation has disclosed details surrounding two severe remote code execution vulnerabilities in PHP that were addressed in updates released on October 21, 2026. The issues, tracked as CVE-2026-109618 and CVE-2026-109619, affect memory management and error handling routines used in nearly every request. Although signs of one flaw were identified during an external audit in 2024, resource constraints and prioritization of other issues delayed remediation. The foundation had planned a coordinated disclosure, but information leaked prematurely, causing confusion among stakeholders. Updated versions PHP 8.5.12, 8.4.27, 8.3.36, and 8.2.35 are now available, and immediate patching is strongly recommended for all users. The vulnerabilities' broad impact and the challenges in balancing security fixes with performance considerations made the response particularly complex.
CISA Urges Immediate Patching of Critical PHP Remote Code Execution Vulnerabilities
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has issued an urgent advisory regarding two severe vulnerabilities in the PHP programming language that allow unauthenticated remote code execution. Identified as CVE-2026-109618 and CVE-2026-109619, the flaws affect all environments processing web requests with PHP and have been nicknamed php2shell. CISA recommends applying patches to PHP 8.5.12, 8.4.27, 8.3.36, or 8.2.35 without delay, or taking affected systems offline if updates cannot be applied immediately. Although no exploitation has been observed yet, organizations are instructed to inventory PHP usage, prioritize internet-facing systems, and monitor for suspicious activity such as shell processes spawned from PHP workers. Web application firewalls may offer partial protection but are not considered a substitute for patching.
PHP Issues Emergency Patches for Critical PHP2Shell RCE Flaws as Exploit Attempts Emerge
PHP has released urgent patches for two critical vulnerabilities collectively known as PHP2Shell that enable unauthenticated remote code execution on affected servers. The flaws, tracked as CVE-2026-109618 and CVE-2026-109619, score 9.2 on CVSS v4.0 and have already seen active exploitation attempts with malicious payloads adjusted to bypass WAF rules. The issues affect multiple PHP deployment methods including Apache with mod_php, PHP-FPM, php-cgi, FrankenPHP, and LiteSpeed, and do not require complex application code to be exploitable. CVE-2026-109618 involves a memory corruption chain leading to code execution under the web process privileges, while CVE-2026-109619 stems from an obsolete global state issue causing use-after-free conditions that can result in memory disclosure and code execution. Patched versions include PHP 8.5.12, 8.4.27, 8.3.36, and 8.2.35, with administrators advised to restart all persistent workers after updating. Temporary mitigations such as setting memory_limit to -1 and disabling session.upload_progress.enabled are available for environments that cannot patch immediately.
Two Critical RCE Vulnerabilities Patched in PHP with CVSS 9.2 Scores
The PHP development team has disclosed two severe remote code execution vulnerabilities affecting the widely used scripting language. Both issues, tracked as CVE-2026-109618 and CVE-2026-109619, received a CVSSv4.0 base score of 9.2 and were rated Critical. The flaws stem from improper memory handling during request processing and cleanup phases. Exploitation could allow attackers to execute arbitrary code by manipulating uninitialized or residual data in worker processes. Security updates addressing both vulnerabilities were released on October 21, 2026, and users are strongly urged to apply the patches immediately. The advisories were previewed the previous day, highlighting the urgency of the fixes.
Critical PHP Core Flaws Enable Unauthenticated Remote Code Execution
The PHP project released emergency patches on October 21 for two critical vulnerabilities in the language core, tracked as CVE-2026-109618 and CVE-2026-109619 and collectively referred to as PHP2Shell. Both issues received a CVSS 4.0 score of 9.2 and allow remote code execution without authentication. CVE-2026-109618 resides in memory-handling routines where longjmp can leave request data partially initialized, and subsequent shutdown operates on invalid data; multipart requests with many headers or empty file fields can trigger the condition. CVE-2026-109619 affects an obsolete global state in long-lived workers that retain references to freed memory, with confirmed paths involving fatal errors, error reporting data, and session upload progress. Researchers demonstrated unauthenticated code execution over HTTP against the first flaw on Apache with mod_php using default limits, while PHP-FPM exposure was identified through code analysis. The FBI Cyber Division issued an alert urging immediate updates, and Cloudflare deployed WAF rules while confirming early attacks in the wild.