AI, in your work.

On 21 October, PHP released updates for two critical vulnerabilities that can allow remote code execution without authentication. Known as PHP2Shell, the case combines AI-assisted research with a response led by maintainers. Fixed releases are on the official downloads page; each operator must determine which update applies to their services.

What has been fixed

The official advisories describe two memory-management problems in the PHP engine. Exploitation paths depend on the version, configuration and way the interpreter runs.

• CVE-2026-109618: an out-of-memory failure can interrupt the initialisation of internal data; subsequent cleanup may use that data as though it were valid.
• CVE-2026-109619: a worker can retain references to freed memory from one request and use them when handling another.

What we know about AI’s contribution

OpenAI credits Calif with a finding using GPT-5.6 Sol and acknowledges Wiz’s independent discovery of both vulnerabilities. PHP’s maintainers led the fixes and release.

In its technical research, Calif explains how the researcher’s prior knowledge of PHP guided analysis with models and describes remote code execution tests across several applications. These are scenarios reproduced by the authors, rather than an audit of every installation.

Wiz separately describes using Wiz Atlas, Gemini 4 Argon and GPT-5.6 Sol, with demonstrations involving WordPress, Drupal and Joomla. These accounts allow contributions to be compared, but do not constitute an independent evaluation isolating how much each model contributed.

Organising the response

Drawing on this experience, OpenAI proposes five stages. Maintainers decide whom to involve before disclosure.

• Validate the finding and test the fix.
• Notify those who need to prepare protections.
• Coordinate the response with government agencies.
• Prepare updates with distributors and providers.
• Publish guidance and support deployment.

Available releases and vendor packages

These are the first fixed upstream releases, available through PHP’s downloads page. The table covers original project releases: a distributor may incorporate the patch without adopting that version number.

PHP notes that 8.1 and earlier lack regular support and links minimal backports for 7.4, 8.0 and 8.1. The availability of patched packages depends on the vendor.

The subsequent advisory that limits the scope

PHP’s 23 October advisory adds CVE-2026-115560: an unlikely path involving a runtime change of `session.serialize_handler` from `php_binary` or `php_serialize` to `php` before `session_start()`, with upload progress enabled. It recommends `session.upload_progress.enabled=0` until the next regular release; applications without that runtime handler change may keep the feature enabled. The advisory does not yet announce that patch.

For the two initial flaws, PHP’s technical advisory states that updating is the only complete mitigation. Temporary measures reduce particular exposure paths and do not amount to installing the fix.

What the public checker can establish

OpenAI’s public PHP Version Checker repository offers URL-based or server-access checks and integration as Codex skills. URL mode reads HTTP headers: it returns `UNKNOWN` when no recognisable version is available. Even `OK` describes only the advertised version, without verifying the installation.

That mode also cannot identify vendor-backported fixes and sends no exploit probes. Its result provides an inventory clue; it needs to be checked against the installed package and the vendor’s advisory.

Nexo’s interpretation: assign responsibility through deployment

Our interpretation is that the case requires three responsibilities to be connected: validating the flaw, deciding on disclosure and checking that the patch is actually installed. An AI-assisted finding does not itself establish that every service is protected.

Hypothetical example: an organisation uses PHP in two services with different providers. It could assign each service owner responsibility for confirming the patched package, deploying it and checking the process handling requests, while security coordinates follow-up. This example illustrates a division of work and does not certify any system.