PatchSiren

PatchSiren cyber security CVE debrief

CVE-2022-37436 Festo Didactic SE CVE debrief

CVE-2022-37436 affects Apache HTTP Server versions prior to 2.4.55 and was published by CISA in the Festo Didactic SE MES PC advisory on 2024-02-27. A malicious backend can cut response headers short, which can move some later headers into the response body. If those later headers were meant to provide security controls, the client will not interpret them. Festo’s remediation notes point operators to a Factory Control Panel replacement for XAMPP on MES PCs.

Vendor
Festo Didactic SE
Product
MES PC
CVSS
MEDIUM 5.3
CISA KEV
Not listed in stored evidence
Original CVE published
2024-02-27
Original CVE updated
2026-01-27
Advisory published
2024-02-27
Advisory updated
2026-01-27

Who should care

Festo Didactic SE MES PC operators, OT/ICS administrators, and teams responsible for Apache HTTP Server-based backend or proxy behavior in the affected MES PC environment.

Technical summary

The issue is a response-handling flaw in Apache HTTP Server prior to 2.4.55. When a malicious backend induces early truncation of response headers, subsequent headers can be incorporated into the body instead of being processed as headers. This is especially relevant when the later headers carry security meaning, because the client will not apply them. The Festo advisory ties the issue to MES PCs and states that Factory Control Panel replaces XAMPP on those systems and includes fixes via the vendor-provided current version.

Defensive priority

Medium. The CVSS score is 5.3, with network reachability and no user interaction required, but the documented impact is limited to integrity of later headers and depends on backend behavior.

Recommended defensive actions

  • Identify MES PCs that use the affected Festo/Factory Control Panel or related Apache HTTP Server stack.
  • Obtain the current Factory Control Panel version from Festo technical support and deploy the vendor fix path described in the advisory.
  • Confirm that any affected Apache HTTP Server instance is updated to 2.4.55 or later where applicable.
  • Review security headers and backend response handling to ensure critical headers are still delivered and interpreted correctly.
  • Monitor for malformed or truncated backend responses in logs and alerting.
  • Use the official CISA and Festo advisories to verify remediation status for the specific MES PC deployment.

Evidence notes

The supplied CISA CSAF source item and the linked Festo advisory describe the flaw as occurring prior to Apache HTTP Server 2.4.55, where a malicious backend can truncate response headers and cause later headers to be treated as body content. The CISA source was initially published on 2024-02-27 and republished on 2026-01-27; those dates reflect advisory publication history, not the original flaw date. Festo’s remediation note states that Factory Control Panel replaces XAMPP on MES PCs and that the current version includes fixes, obtainable via technical support.

Official resources

CVE published 2024-02-27; CISA’s source item was initially published the same day and later republished on 2026-01-27. Treat the CVE publication date as the issue publication context, not the later republication date.