CVE-2023-5330 in Mattermost
Summary
by MITRE • 10/25/2023
Mattermost fails to enforce a limit for the size of the cache entry for OpenGraph data allowing an attacker to send a specially crafted request to the /api/v4/opengraph filling the cache and turning the server unavailable.
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Analysis
by VulDB Data Team • 10/25/2023
The vulnerability identified as CVE-2023-5330 represents a critical denial of service weakness within the Mattermost collaborative platform that specifically targets the OpenGraph data caching mechanism. This flaw resides in the application's handling of metadata extraction for shared links, where the system fails to implement adequate size limitations for cache entries. The vulnerability manifests when an attacker crafts malicious requests to the /api/v4/opengraph endpoint, exploiting the absence of validation controls on cache entry sizes. OpenGraph data is commonly used to generate rich previews when users share web links within the platform, making this functionality integral to the user experience but also creating a potential attack vector.
The technical implementation of this vulnerability stems from inadequate input validation and resource management within the OpenGraph processing pipeline. When Mattermost receives a request to fetch OpenGraph metadata for a URL, it stores this information in a cache for subsequent use. Without proper size limits, an attacker can submit crafted OpenGraph data that exceeds normal parameters, potentially causing cache entries to consume excessive memory resources. This behavior aligns with CWE-1321, which addresses the lack of limits on cache entry sizes, and can be categorized under the broader category of resource exhaustion vulnerabilities. The attack vector specifically targets the server's memory management capabilities through the API endpoint, allowing for a form of cache poisoning that can lead to service degradation.
The operational impact of CVE-2023-5330 extends beyond simple service disruption to potentially compromise the overall availability and stability of Mattermost deployments. When cache entries grow unchecked, they can consume significant server memory resources, leading to performance degradation, application slowdowns, or complete service unavailability. This vulnerability particularly affects organizations relying on Mattermost for critical communications, where sustained denial of service could impact business operations. The attack can be executed with minimal resources and technical expertise, making it a particularly dangerous threat that could be exploited by both malicious actors and automated systems. The vulnerability also introduces potential cascading effects where a single malicious request can cause widespread impact across the entire platform.
Mitigation strategies for CVE-2023-5330 should focus on implementing robust size limitations for cache entries and strengthening input validation mechanisms within the OpenGraph processing pipeline. Organizations should configure maximum size limits for OpenGraph data entries to prevent excessive memory consumption, while also implementing rate limiting controls to restrict the frequency of requests to the affected API endpoint. The solution aligns with ATT&CK technique T1499.004, which addresses resource exhaustion attacks through proper input validation and limiting mechanisms. Additionally, implementing proper monitoring and alerting systems can help detect anomalous cache usage patterns that may indicate exploitation attempts. Regular security updates and patches should be applied immediately upon availability, while organizations should also consider implementing network-level controls to restrict access to the vulnerable API endpoint when possible. The fix should also include comprehensive logging of cache operations to enable forensic analysis and incident response activities.