Informational advisory: Session upload progress
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.