Description

Improper input validation in the capabilities route handler in OpenSearch Dashboards - the size of the request payload is not bounded - might allow remote attackers to cause a denial of service via a crafted HTTP request.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.5",
  "pubDate": "2026-08-18T17:17:03.310Z",
  "pubdate": "2026-08-18T17:17:03.310Z",
  "executiveSummary": "An improper input validation vulnerability exists within the capabilities route handler of OpenSearch Dashboards, specifically characterized by the failure to bound the size of incoming request payloads. This security flaw introduces a significant denial of service risk affecting OpenSearch Dashboards deployments. A remote attacker with network access can exploit this vulnerability by transmitting a specially crafted HTTP request containing an excessively large payload to the vulnerable endpoint. Successful exploitation overwhelms server resources, leading to service degradation, application unresponsiveness, or complete availability loss. The risk implications are critical for environments relying on continuous availability of observability and visualization dashboards, as the attack vector requires minimal attacker capabilities beyond network connectivity to the target HTTP route handler. Remediation requires implementing strict payload size limits and robust input validation mechanisms within the affected capabilities route handler.",
  "technicalDetails": "The root cause of the vulnerability resides in the capabilities route handler of OpenSearch Dashboards, which fails to enforce strict boundary checks and size validation on incoming HTTP request payloads. When the application processes the capabilities route, it reads and parses the incoming data stream without imposing maximum length or size constraints.\nThe vulnerable component is the capabilities route handler within the OpenSearch Dashboards backend routing and request-handling architecture. The affected protocol is HTTP, exposed remotely over the network to any client capable of reaching the Dashboards service port.\nExploitation occurs via a crafted HTTP request directed at the capabilities route handler. An unauthenticated or authenticated remote attacker transmits an HTTP payload with an arbitrarily large size—often consisting of deeply nested JSON structures or massive string data. Because the route handler lacks proper input validation and bound checking, the Node.js runtime environment attempts to buffer, parse, and process the entire oversized payload into memory.\nThe attack flow proceeds as follows: First, the attacker identifies the exposed capabilities route handler endpoint in OpenSearch Dashboards. Second, the attacker crafts a malicious HTTP request embedding a high-volume payload designed to consume excessive computational cycles and memory allocations. Third, upon receiving the request, the application layer allocates disproportionate system resources to handle the unbounded input. Finally, memory exhaustion or CPU saturation ensues, resulting in a denial of service condition where legitimate user requests are dropped or fail to process, ultimately crashing the OpenSearch Dashboards process or rendering it entirely inaccessible.\nAuthentication and privilege requirements depend on the default routing configuration of the specific OpenSearch Dashboards deployment, but remote exploitation via the network vector allows external actors to disrupt service availability. Post-exploitation impact is strictly localized to availability, causing application-level or host-level denial of service without directly facilitating remote code execution or unauthorized data exfiltration based on the provided vulnerability description."
}