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PatchSiren cyber security CVE debrief

CVE-2023-27522 Festo Didactic SE CVE debrief

CVE-2023-27522 is a high-severity HTTP response smuggling issue in Apache HTTP Server's mod_proxy_uwsgi path. The advisory says special characters in the origin response header can truncate or split the response forwarded to the client. CISA's CSAF advisory maps the issue to Festo Didactic SE's MES PC environment and points to a replacement product, Factory Control Panel, as the vendor remediation.

Vendor
Festo Didactic SE
Product
MES PC
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2025-02-25
Original CVE updated
2025-02-25
Advisory published
2025-02-25
Advisory updated
2025-02-25

Who should care

Administrators and support teams responsible for Festo Didactic SE MES PC deployments, plus anyone running Apache HTTP Server 2.4.30 through 2.4.55 with mod_proxy_uwsgi enabled. Security teams should review exposed web front ends and any upstream proxy chains that depend on this module.

Technical summary

The vulnerable condition is in Apache HTTP Server via mod_proxy_uwsgi. According to the advisory, special characters in an origin response header can cause the forwarded response to be truncated or split before reaching the client. The affected Apache versions are 2.4.30 through 2.4.55. The provided CVSS vector is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N, scoring 7.5.

Defensive priority

High. The issue is network-reachable, requires no privileges or user interaction, and is rated High by CVSS. Treat it as priority remediation for any affected Apache deployments and for MES PC systems that depend on the vulnerable stack.

Recommended defensive actions

  • Inventory Apache HTTP Server deployments and confirm whether mod_proxy_uwsgi is enabled on versions 2.4.30 through 2.4.55.
  • Apply the vendor-provided remediation path referenced in the advisory; for MES PCs, obtain the current Factory Control Panel version from Festo technical support.
  • Replace or upgrade affected components before re-exposing the service to users or upstream systems.
  • Validate reverse proxy and backend response handling after remediation to ensure the smuggling condition is no longer present.
  • Use CISA ICS recommended practices to reduce exposure and improve segmentation, monitoring, and change control around the affected service.

Evidence notes

Source evidence comes from the CISA CSAF advisory ICSA-26-027-02 and its referenced material. The advisory text states that the issue affects Apache HTTP Server 2.4.30 through 2.4.55 and that special characters in the origin response header can truncate or split the response forwarded to the client. The source also lists Festo Didactic SE MES PC as the affected product context and identifies Factory Control Panel as the remediation path. The CVSS vector supplied in the advisory is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

Sources and references

Verified primary and authoritative sources

  • CVE-2023-27522 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2023-27522

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2023-27522 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2023-27522

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/OT/white/2026/icsa-26-027-02.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://festo.csaf-tp.certvde.com/.well-known/csaf/white/2024/fsa-202402.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://certvde.com/en/advisories/vendor/festo/

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://festo.com/psirt

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://certvde.com/en/advisories/VDE-2023-065

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-26-027-02

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-alerts/ics-alert-10-301-01

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/resources-tools/resources/ics-recommended-practices

    Reference

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.