CVE-2026-73057 in stoatchat
Summary
by MITRE • 08/16/2026
stoatchat before 0.15.0 fails to validate SVG viewBox dimensions in the proxy endpoint, allowing attackers to cause denial of service by memory exhaustion. Attackers can host malicious SVGs with extremely large width and height values and trigger concurrent requests to exhaust available memory across proxy replicas.
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Analysis
by VulDB Data Team • 08/16/2026
The vulnerability identified in stoatchat versions prior to 0.15.0 represents a critical resource management flaw within the application's image processing pipeline, specifically affecting the handling of Scalable Vector Graphics (SVG) files through its proxy endpoint. This issue stems from an insufficient validation mechanism for the viewBox attributes embedded within SVG documents. When users or automated systems request images via the proxy, the backend service attempts to parse and potentially resize these graphics. However, because the application fails to enforce reasonable bounds on the width and height dimensions specified in the SVG's viewBox attribute, it allows attackers to inject maliciously crafted files containing extremely large coordinate values. This lack of input sanitization creates a direct pathway for resource exhaustion attacks against the service infrastructure.
From a technical perspective, this flaw is classified under CWE-400, which describes uncontrolled resource consumption. The vulnerability exploits the way modern web servers and image processing libraries handle vector graphics rendering. When an SVG with massive viewBox dimensions is processed, the underlying library may attempt to allocate memory proportional to these dimensions to create a rasterized representation or perform geometric calculations. By hosting malicious SVGs on external servers and triggering concurrent requests from multiple sources or through automated scripts, attackers can force the proxy replicas to consume excessive amounts of RAM. This behavior leads to a denial of service condition where legitimate users are unable to access services due to memory exhaustion across the cluster. The attack vector is particularly effective because it leverages standard HTTP GET requests, making it difficult to distinguish from benign traffic without deep packet inspection or strict rate limiting policies that account for payload size and complexity.
The operational impact of this vulnerability extends beyond simple service unavailability. In a distributed environment with multiple proxy replicas, the exhaustion of memory on one node can lead to cascading failures if load balancers continue to route traffic to affected instances. This results in degraded performance for all users relying on the stoatchat platform and potentially causes data loss or corruption during abrupt process terminations triggered by out-of-memory errors. Furthermore, this vulnerability aligns with ATT&CK technique T1498, Network Denial of Service, specifically under the sub-technique of resource exhaustion via application layer attacks. It highlights a common oversight in web applications where input validation is focused on security threats like injection but neglects availability concerns related to parsing complexity and resource allocation limits.
To mitigate this vulnerability, immediate action should be taken by upgrading stoatchat to version 0.15.0 or later, which includes the necessary fixes for SVG dimension validation. For organizations unable to upgrade immediately, defensive measures must be implemented at the network perimeter. Web Application Firewalls (WAF) can be configured to inspect incoming requests and block payloads containing SVG files with viewBox dimensions exceeding a predefined safe threshold. Additionally, implementing strict rate limiting on the proxy endpoint can help mitigate the impact of concurrent attacks by throttling excessive request volumes from single IP addresses or user agents. It is also advisable to configure server-side resource limits using tools like ulimit in Linux environments or container memory constraints in Kubernetes clusters to ensure that even if an attack succeeds, it does not compromise the stability of the entire host system. Regular security audits focusing on input validation and resource management practices should be conducted to prevent similar issues in other parts of the application stack.