PHP advisory: disable session upload progress to prevent another unlikely RCE
php.net
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.