CVE-2018-19935 Festo Didactic SE CVE debrief

Who should care

Administrators and OT/industrial IT teams responsible for Festo Didactic SE MES PC deployments, especially systems using PHP 5.x or 7.x before 7.3.0 or related XAMPP/Factory Control Panel components referenced in the advisory.

Technical summary

The advisory describes a remote denial-of-service condition in ext/imap/php_imap.c. If imap_mail is called with an empty string in the message argument, the affected PHP versions can dereference NULL and crash the application. The supplied CVSS vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) matches a network-reachable, no-privileges, no-user-interaction availability impact. The source corpus ties the issue to Festo Didactic SE MES PC, while the underlying flaw is in PHP before 7.3.0.

Defensive priority

High for any exposed MES PC or PHP/imap deployment using the affected component, because the bug is remotely triggerable and can cause immediate service interruption.

Recommended defensive actions

• Confirm whether any MES PC environment uses PHP 5.x or 7.x before 7.3.0, or other affected ext/imap deployments.
• Install the supported vendor replacement referenced in the advisory: Factory Control Panel/current Festo-supported release for MES PCs.
• Remove or retire unsupported XAMPP/PHP stacks where possible, especially on systems that must remain available.
• Add server-side input validation so empty message arguments are rejected before imap_mail is invoked.
• Restrict network exposure to MES PC services and apply segmentation and defense-in-depth controls to reduce denial-of-service impact.
• Monitor PHP/application logs for crashes or restarts involving imap-related services and verify recovery procedures and backups.

Evidence notes

The supplied source item is a CISA CSAF republication for Festo Didactic SE MES PC and explicitly describes the PHP ext/imap NULL pointer dereference when imap_mail receives an empty message string. The advisory metadata provides the CVSS 3.1 vector AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, supporting a remote, no-privileges, high-availability-impact assessment. The corpus also includes an original vendor advisory reference and a remediation entry dated 2023-05-26, while the public CISA republished item used here was published on 2024-02-27 and later modified on 2026-01-27; those dates describe advisory publication history, not the vulnerability’s origin.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.