The PHP team announces updated Windows builds: PHP 8.5.12-1, 8.4.27-1, 8.3.36-1 and 8.2.35-1. These builds include Brotli 1.2.1, which fixes CVE-2026-111497, an out-of-bounds write vulnerability in Brotli decompression.

In PHP Windows builds, the vulnerable decoder can be reached through the cURL extension when automatic HTTP response decompression is enabled. This is disabled by default in cURL, but applications and HTTP client libraries can enable it.

The -1 suffix identifies a Windows package rebuild with updated dependencies. These builds use the same PHP source releases, and the PHP runtime versions remain unchanged.

The updated packages are available on the downloads page.

We suggest you set session.upload_progress.enabled=0 until the next regular bugfix release, to fully protect from an unlikely RCE vector. This setting was already listed as a mitigation in the GHSA-6wmf-4rv5-p3rp advisory for CVE-2026-109619 published on Oct 21st, 2026. If you applied it then, keep it in place and no further action is needed.

The issue can only occur under an unusual combination of configuration and application code. An application must set session.serialize_handler to php_binary or php_serialize in its configuration and then switch it to php at runtime with ini_set() before calling session_start(). Session upload progress must also still be enabled. Applications that never change the serialize handler at runtime can keep the feature enabled. Since this setup is unlikely in practice, we are handling it in the regular release cycle and will publish a full advisory for CVE-2026-115560 with the next release.

The PHP team is pleased to announce the third release candidate of PHP 8.6.0, RC4. This continues the PHP 8.6 release cycle, whose rough outline is specified in the PHP Wiki.

Source downloads of PHP 8.6.0 RC4 are available on the download page.

Please carefully test this version and report any issues found in the GitHub Issues.

This version also contains the fixes for two critical vulnerabilities that can allow unauthenticated remote code execution. Everyone running earlier builds of PHP 8.6.0 is strongly encouraged to update immediately.

Please DO NOT use this version in production, it is an early test version.

For more information on the new features and other changes, you can read the NEWS file, or the UPGRADING file for a complete list of upgrading notes. These files can also be found in the release archive.

The next release will be the last release candidate (RC5), planned for 5 November 2026.

The signatures for the release can be found in the manifest or on the pre-release builds page.

Thank you for helping us make PHP better.

PHP 8.5.12, 8.4.27, 8.3.36 and 8.2.35 fix two critical vulnerabilities that can allow unauthenticated remote code execution. All PHP users are strongly encouraged to update immediately.

Who is at risk: all PHP installations serving web requests, including PHP-FPM, Apache with mod_php, php-cgi, FrankenPHP and LiteSpeed. We consider the risk highest for mod_php, with a demonstrated exploit where an unauthenticated request can trigger the attack before any application code runs.

The vulnerabilities:

• RCE via OOM corruption, CVE-2026-109618 (GHSA-w8hw-w9fx-j79w): out-of-memory handling can interrupt PHP while internal request data is only partially initialized. Request cleanup may then treat the invalid data as valid.
• RCE via stale global state, CVE-2026-109619 (GHSA-6wmf-4rv5-p3rp): request-owned internal state can survive after its backing memory has been freed. A later request handled by the same worker may use that stale state before normal initialization resets it.

How to update:

• Update to PHP 8.5.12, 8.4.27, 8.3.36 or 8.2.35. Source downloads are on our downloads page. Windows source and binaries are on the same page.
• Linux distributions and LTS vendors received the patches in advance, so check your vendor for updated packages.
• PHP 8.1 and older no longer receive updates from the PHP project. Some distributions and LTS vendors provide backported fixes, so contact your vendor for details, or upgrade to a supported version.
• Given the severity of these vulnerabilities, the PHP security team provided minimal source-backports for PHP 7.4, PHP 8.0, and PHP 8.1 to help people building from source or without access to an LTS vendor.

If you cannot update immediately: while only an update is a complete solution, the following measures reduce exposure to specific attack paths but do not make an installation safe.

RCE via OOM corruption (CVE-2026-109618):

• Set memory_limit=-1, preferably in a way applications can't override, such as php_admin_value in the FPM pool or Apache configuration, and check that no pool, directory or application setting puts a finite limit back. This removes the controllable PHP memory limit failure, but an underlying allocation failure can still reach the vulnerable path.
• Set a low post_max_size. For applications that don't require file uploads, set post_max_size = 8M. If file uploads are necessary, set post_max_size = 32M. Keep upload_max_filesize below post_max_size. Consider enforcing limits at the web server or proxy level for decoded request size, input field count, multipart part count, header count, and nesting depth. These limits must also cover requests without a usable Content-Length.
• Use a container or cgroup limit as an availability boundary, preferably with a policy that kills only the affected worker. Do not substitute RLIMIT_AS or RLIMIT_DATA, as these can cause the vulnerable allocation failure.

RCE via stale global state (CVE-2026-109619):

• Set session.upload_progress.enabled=0 and restart every worker. Use php.ini, an FPM pool or server configuration that applies before request parsing. Do not rely on ini_set() or FPM .user.ini. This blocks the confirmed session paths but not other variants.
• On PHP 8.5, set fatal_error_backtraces=0 and restart every worker. This blocks the confirmed fatal backtrace path only.
• Remove invalid or deprecated settings applied per request that emit diagnostics before initialization. Hiding diagnostics with error_reporting, display_errors or @ does not help.
• Fix attacker-reachable fatal errors and execution timeouts, including failures in callbacks, upload or import processing and cleanup.

The advisories linked above have the full technical details.

The PHP development team announces the immediate availability of PHP 8.5.12. This is a security release fixing two critical vulnerabilities (CVE-2026-109618, CVE-2026-109619) that can allow unauthenticated remote code execution. All PHP 8.5 users are strongly encouraged to update immediately.

There are no complete mitigations, updating is the only safe choice. See the security advisory for details.

For source downloads of PHP 8.5.12 please visit our downloads page, Windows source and binaries can also be found there. The list of changes is recorded in the ChangeLog.