CVE-2024-4182 in Mattermost
Summary
by MITRE • 04/26/2024
Mattermost versions 9.6.0, 9.5.x before 9.5.3, 9.4.x before 9.4.5, and 8.1.x before 8.1.12 fail to handle JSON parsing errors in custom status values, which allows an authenticated attacker to crash other users' web clients via a malformed custom status.
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Analysis
by VulDB Data Team • 05/12/2025
The vulnerability identified as CVE-2024-4182 affects Mattermost server versions across multiple release branches including 9.6.0, 9.5.x prior to 9.5.3, 9.4.x prior to 9.4.5, and 8.1.x prior to 8.1.12. This issue stems from inadequate error handling during JSON parsing operations within the custom status functionality, representing a critical security flaw that impacts the overall stability and availability of the messaging platform. The vulnerability specifically targets the server's ability to process user-defined custom status values, which are commonly used in enterprise communication systems for indicating user availability, work status, or other contextual information.
The technical flaw manifests when the Mattermost server encounters malformed JSON data within custom status fields submitted by authenticated users. During normal operation, the server should validate and properly parse JSON structures to ensure data integrity and prevent system instability. However, the affected versions lack proper exception handling mechanisms that would gracefully manage malformed JSON input, leading to unhandled exceptions that cause the server to crash or become unresponsive. This failure to handle JSON parsing errors creates a potential denial of service condition that extends beyond the immediate user context to affect other connected clients within the same Mattermost instance.
The operational impact of this vulnerability extends significantly beyond simple service disruption, as it enables authenticated attackers to target other users' web clients specifically through crafted malicious input. When an attacker successfully submits malformed JSON within a custom status field, the affected server processes this data and subsequently crashes the web clients of other users who are connected to the same Mattermost instance. This creates a cascading effect where legitimate users experience sudden disconnections or client instability, potentially disrupting critical communication workflows in enterprise environments where Mattermost serves as a primary collaboration platform. The vulnerability demonstrates characteristics consistent with CWE-248, an unspecified flaw in the handling of data parsing operations, and aligns with ATT&CK technique T1499.004 for network denial of service attacks through application layer manipulation.
The security implications of this vulnerability are particularly concerning given that it requires only authenticated access to exploit, meaning that any user with valid credentials within the Mattermost environment can potentially launch this attack against other users. This makes the vulnerability particularly dangerous in shared or multi-tenant environments where privilege escalation or lateral movement may not be required to cause disruption. Organizations relying on Mattermost for business communication may experience significant operational disruption when this vulnerability is exploited, as users lose access to their messaging clients and potentially lose access to critical information during the period of service disruption. The vulnerability also represents a potential vector for more sophisticated attacks that could leverage the instability to gain additional system access or escalate privileges within the affected environment.
Mitigation strategies for CVE-2024-4182 should focus on immediate patch deployment across all affected Mattermost server versions, with particular attention to the specific version ranges mentioned in the vulnerability description. Organizations should implement network monitoring to detect potential exploitation attempts through unusual JSON parsing patterns or client disconnection events. Additionally, administrators should consider implementing input validation mechanisms at the application level to sanitize custom status values before processing, though this represents a temporary workaround until official patches are applied. The recommended approach aligns with security best practices outlined in NIST SP 800-53 and ISO 27001 frameworks for vulnerability management and application security hardening. Regular security assessments should be conducted to ensure proper configuration of custom status functionality and to verify that all patched versions are properly deployed across the organization's Mattermost infrastructure.