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CVE-2023-38709 Apache Software Foundation CVE debrief

CVE-2023-38709 is a medium-severity HTTP response splitting vulnerability in Apache HTTP Server, affecting versions through 2.4.58. The flaw stems from faulty input validation in Apache's core, allowing malicious or exploitable backend/content generators to split HTTP responses. This vulnerability was published on November 12, 2024, with a CVSS 3.1 score of 6.1 (MEDIUM). Siemens SINEC NMS is identified as an affected product in this advisory. The vulnerability enables response splitting attacks where attackers can manipulate HTTP headers, potentially leading to cache poisoning, cross-site scripting, or session fixation when user-controlled input is reflected in HTTP response headers without proper sanitization. Siemens has provided a vendor fix: update to SINEC NMS V3.0 SP1 or later version.

Vendor
Apache Software Foundation
Product
SINEC NMS
CVSS
MEDIUM 6.1
CISA KEV
Not listed in stored evidence
Original CVE published
2024-11-12
Original CVE updated
2024-11-12
Advisory published
2024-11-12
Advisory updated
2024-11-12

Who should care

Organizations running Siemens SINEC NMS for industrial network management should prioritize this update. Security teams managing Apache HTTP Server deployments in industrial control system (ICS) environments should assess exposure. Network administrators responsible for OT/ICS infrastructure should review backend content generators for proper input validation. Compliance teams tracking CVE remediation for critical infrastructure should note this CISA-coordinated advisory.

Technical summary

CVE-2023-38709 is an HTTP response splitting vulnerability in Apache HTTP Server core through version 2.4.58. The vulnerability exists due to insufficient input validation when processing data from backend content generators. Malicious or compromised backend components can inject CRLF (carriage return/line feed) sequences into HTTP response headers, causing the server to interpret a single response as multiple responses. This can lead to cache poisoning, XSS, or session fixation attacks. The vulnerability affects Siemens SINEC NMS, which incorporates the vulnerable Apache HTTP Server component. HTTP response splitting occurs when attacker-controlled data containing header-terminating sequences is unsafely reflected into HTTP response headers without proper sanitization, allowing the attacker to control the structure of the HTTP response.

Defensive priority

medium

Recommended defensive actions

  • Apply the vendor-provided update to SINEC NMS V3.0 SP1 or later version to remediate this vulnerability
  • Review and validate all backend content generators and CGI scripts that may pass user-controlled input to HTTP response headers
  • Implement input validation and sanitization for any data reflected in HTTP headers, removing CRLF sequences and other header control characters
  • Consider deploying web application firewalls (WAFs) with rules to detect and block HTTP response splitting attempts
  • Monitor for anomalous HTTP responses and cache behavior that may indicate exploitation attempts
  • Follow CISA ICS recommended practices for defense-in-depth strategies in industrial control environments

Evidence notes

CVE published 2024-11-12. CVSS 6.1 MEDIUM. Affects Apache HTTP Server through 2.4.58. Siemens SINEC NMS affected. Vendor fix available: update to V3.0 SP1 or later.

Official resources

2024-11-12