CVE-2022-23500 in TYPO3
Summary
by MITRE • 12/14/2022
TYPO3 is an open source PHP based web content management system. In versions prior to 9.5.38, 10.4.33, 11.5.20, and 12.1.1, requesting invalid or non-existing resources via HTTP triggers the page error handler, which again could retrieve content to be shown as an error message from another page. This leads to a scenario in which the application is calling itself recursively - amplifying the impact of the initial attack until the limits of the web server are exceeded. This vulnerability is very similar, but not identical, to the one described in CVE-2021-21359. This issue is patched in versions 9.5.38 ELTS, 10.4.33, 11.5.20 or 12.1.1.
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Analysis
by VulDB Data Team • 01/08/2023
The vulnerability identified as CVE-2022-23500 represents a critical recursive resource handling flaw within the TYPO3 content management system that manifests through improper error message generation mechanisms. This issue affects multiple major versions of TYPO3 including 9.5.x prior to 9.5.38, 10.4.x prior to 10.4.33, 11.5.x prior to 11.5.20, and 12.1.x prior to 12.1.1, creating a persistent security risk across the TYPO3 ecosystem. The vulnerability stems from the application's error handling mechanism that attempts to retrieve content from other pages when displaying error messages for invalid or non-existent resources, creating a dangerous recursive loop that can be exploited by malicious actors.
The technical implementation of this vulnerability involves the page error handler component within TYPO3's architecture which, when processing HTTP requests for non-existent resources, attempts to fetch content from alternative pages to construct informative error messages. This design flaw creates a scenario where the error handling mechanism itself becomes a vector for recursive processing, as the system calls itself repeatedly to generate error content. The recursive nature of this flaw is particularly dangerous because it can exponentially amplify the initial attack payload, causing the web server to consume increasing amounts of computational resources until it reaches system limits or crashes entirely. This behavior aligns with common patterns found in denial of service attacks and can be classified under CWE-400 as an Uncontrolled Resource Consumption vulnerability.
The operational impact of CVE-2022-23500 extends beyond simple service disruption to potentially compromise entire web server infrastructures through resource exhaustion. Attackers can exploit this vulnerability by crafting malicious requests that trigger the recursive error handling mechanism, leading to massive consumption of CPU cycles, memory, and network resources. The vulnerability's similarity to CVE-2021-21359 demonstrates a pattern of recursive processing flaws that have plagued web applications, though each instance requires specific mitigation approaches. The recursive nature of the vulnerability means that even small initial requests can generate massive resource consumption, making it particularly effective for low-cost denial of service attacks. This characteristic places the vulnerability in the ATT&CK matrix under the T1499.004 technique for Network Denial of Service, as it exploits resource exhaustion to prevent legitimate service access.
Mitigation strategies for CVE-2022-23500 require immediate implementation of the patched versions mentioned in the advisory, specifically versions 9.5.38 ELTS, 10.4.33, 11.5.20, or 12.1.1, as these releases contain the necessary code modifications to prevent the recursive error handling behavior. Organizations should also implement additional protective measures including rate limiting on error handling requests, monitoring for unusual resource consumption patterns, and implementing web application firewalls that can detect and block recursive request patterns. The fix addresses the core issue by modifying how TYPO3's error handling system processes invalid resource requests, preventing the system from calling itself recursively while maintaining proper error message generation. Security teams should conduct thorough testing of the patched versions to ensure that legitimate error handling functionality remains intact while the vulnerability is eliminated.