CVE-2023-23616 in Discourse
Summary
by MITRE • 01/28/2023
Discourse is an open-source discussion platform. Prior to version 3.0.1 on the `stable` branch and 3.1.0.beta2 on the `beta` and `tests-passed` branches, when submitting a membership request, there is no character limit for the reason provided with the request. This could potentially allow a user to flood the database with a large amount of data. However it is unlikely this could be used as part of a DoS attack, as the paths reading back the reasons are only available to administrators. Starting in version 3.0.1 on the `stable` branch and 3.1.0.beta2 on the `beta` and `tests-passed` branches, a limit of 280 characters has been introduced for membership requests.
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Analysis
by VulDB Data Team • 10/14/2025
The vulnerability identified as CVE-2023-23616 affects Discourse, an open-source discussion platform that serves as a collaborative forum solution for communities and organizations. This issue stems from insufficient input validation mechanisms within the membership request submission process, specifically concerning the optional reason field that users can provide when requesting membership. The flaw exists in versions prior to 3.0.1 on the stable branch and 3.1.0.beta2 on the beta and tests-passed branches, creating a potential vector for data integrity and system resource management concerns within the platform's database infrastructure.
The technical nature of this vulnerability can be categorized under CWE-120, which represents "Buffer Overflow" or more specifically "Improper Restriction of Operations within the Bounds of a Memory Buffer" in the context of database storage limitations. The core flaw manifests as the absence of character limit enforcement for the membership request reason field, allowing malicious or excessive users to submit arbitrarily large amounts of data. While the system does not impose any restrictions on the length of the reason text provided during membership requests, this lack of validation creates a potential for database bloat and resource consumption issues that could impact overall system performance and storage management.
The operational impact of this vulnerability extends beyond simple data storage concerns to encompass broader system resource management implications. Although the paths that read back these membership request reasons are restricted to administrative users only, the potential for database flooding remains significant. An attacker could theoretically submit membership requests containing massive amounts of data, potentially leading to increased storage requirements, slower database performance, and increased backup times. The vulnerability represents a classic case of insufficient input sanitization that could contribute to resource exhaustion scenarios, though the limited access to read operations somewhat mitigates the direct attack surface.
The remediation implemented in versions 3.0.1 and 3.1.0.beta2 addresses this issue by introducing a 280-character limit for membership request reasons, effectively preventing the submission of excessively large data payloads. This fix aligns with security best practices for input validation and demonstrates the importance of implementing proper data size restrictions in web applications. From an ATT&CK framework perspective, this vulnerability relates to T1499.004, which covers "Cloud Storage Data Destruction" and "Data Manipulation" through resource exhaustion techniques, though the actual attack vector is more limited due to access controls on read operations. The implementation of character limits represents a fundamental defense-in-depth approach that prevents potential exploitation while maintaining the platform's core functionality for legitimate users.