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CVE-2023-45648 Siemens CVE debrief

CVE-2023-45648 is an improper input validation vulnerability in Apache Tomcat affecting versions 11.0.0-M1 through 11.0.0-M11, 10.1.0-M1 through 10.1.13, 9.0.0-M1 through 9.0.81, and 8.5.0 through 8.5.93. The vulnerability stems from incorrect parsing of HTTP trailer headers, where a specially crafted invalid trailer header could cause Tomcat to treat a single request as multiple requests. This creates a request smuggling risk when Tomcat is deployed behind a reverse proxy. The vulnerability was published on August 13, 2024, and affects Siemens SINEC NMS, which incorporates the vulnerable Tomcat component. Siemens has released a vendor fix recommending update to version 3.0 or later. The CVSS 3.1 score of 5.3 (Medium) reflects network attack vector with low attack complexity, no privileges required, no user interaction, and low integrity impact. This vulnerability is not listed in CISA's Known Exploited Vulnerabilities catalog.

Vendor
Siemens
Product
SINEC NMS
CVSS
MEDIUM 5.3
CISA KEV
Not listed in stored evidence
Original CVE published
2024-08-13
Original CVE updated
2024-08-13
Advisory published
2024-08-13
Advisory updated
2024-08-13

Who should care

Organizations running Siemens SINEC NMS for industrial network management should prioritize patching. Additionally, any security teams managing Apache Tomcat deployments behind reverse proxies—including load balancers, WAFs, or CDN edges—should assess exposure, particularly in shared hosting or multi-tenant environments where request smuggling poses elevated risk.

Technical summary

The vulnerability exists in Apache Tomcat's HTTP trailer header parsing logic. Trailer headers are headers that appear after the message body in chunked transfer encoding. Tomcat's improper validation of these headers allows a malformed trailer to be interpreted as a request boundary delimiter. When Tomcat sits behind a reverse proxy, this parsing error can desynchronize the request/response stream between the proxy and backend server—an attack class known as HTTP request smuggling. The attack requires network access to send crafted HTTP requests but no authentication. Successful exploitation could allow request queue manipulation, cache poisoning, or credential hijacking in multi-tenant environments. The fix corrects trailer header validation to reject malformed sequences that could be misinterpreted as request delimiters.

Defensive priority

medium

Recommended defensive actions

  • Upgrade Siemens SINEC NMS to version 3.0 or later per vendor guidance
  • Review Apache Tomcat deployments behind reverse proxies for affected versions (11.0.0-M1-M11, 10.1.0-M1-10.1.13, 9.0.0-M1-9.0.81, 8.5.0-8.5.93)
  • Apply Apache Tomcat updates to fixed versions: 11.0.0-M12+, 10.1.14+, 9.0.81+, or 8.5.94+
  • Validate HTTP trailer header handling in reverse proxy configurations
  • Monitor for anomalous request patterns indicative of request smuggling attempts

Evidence notes

Vulnerability description and affected versions confirmed via CISA CSAF advisory ICSA-24-228-06. Siemens SINEC NMS identified as affected product through CSAF product tree with high confidence. Remediation guidance sourced from vendor remediation field in CSAF document. CVSS vector and score derived from source metadata.

Official resources

2024-08-13