CVE-2026-58371 in SeaweedFS
Summary
by MITRE • 06/30/2026
SeaweedFS before 4.30 reflects the callback query parameter verbatim into responses served with Content-Type application/javascript in the shared writeJson helper (weed/server/common.go), with no callback-name validation, no X-Content-Type-Options: nosniff header, and no CORS allow-list. Every JSON endpoint that uses writeJson - including the unauthenticated master endpoints /dir/status, /dir/lookup and /cluster/status, the volume server /status, and the filer directory listing, all reachable in the default configuration (no -whiteList, no security.toml, bound to 0.0.0.0) - can therefore be loaded cross-origin via a script tag with a chosen callback, letting a third-party web page read cluster topology, volume server URLs and gRPC ports, file identifiers, and directory listings. Because the callback string is reflected at the start of the body and no nosniff header is sent, MIME-sniffing clients may also interpret the reflected content as HTML.
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Analysis
by VulDB Data Team • 06/30/2026
This vulnerability represents a critical cross-origin resource sharing (CORS) misconfiguration and JSONP callback injection flaw in SeaweedFS versions prior to 4.30. The core technical issue resides in the shared writeJson helper function located in weed/server/common.go which processes all JSON responses without proper validation of the callback parameter. When a callback query parameter is provided, the system reflects this value verbatim at the beginning of the response body while serving content with Content-Type application/javascript, creating a classic JSONP security vulnerability that allows arbitrary code execution through cross-origin script loading.
The operational impact of this vulnerability extends across multiple endpoints within the SeaweedFS ecosystem including unauthenticated master endpoints such as /dir/status, /dir/lookup, and /cluster/status, along with volume server /status and filer directory listing functionality. These endpoints are accessible by default without any authentication requirements or access controls when deployed with standard configurations that lack security.toml files or whitelist restrictions. The vulnerability enables attackers to construct malicious web pages that load SeaweedFS endpoints via script tags with custom callback parameters, thereby extracting sensitive cluster topology information, volume server URLs, gRPC port details, file identifiers, and directory listings. This information disclosure represents a significant risk to system security and operational integrity as it provides adversaries with comprehensive knowledge of the storage infrastructure configuration.
The vulnerability manifests due to the absence of several critical security headers including X-Content-Type-Options: nosniff which would prevent MIME-sniffing behavior, and proper CORS allow-listing mechanisms that would restrict cross-origin access to these endpoints. Without these protections, browsers that perform MIME-sniffing may interpret the reflected JSONP content as HTML instead of JavaScript, potentially enabling additional attack vectors such as cross-site scripting or HTML injection. This vulnerability maps directly to CWE-94 (Improper Control of Generation of Code) and CWE-346 (Origin Validation Error) within the Common Weakness Enumeration framework, while also aligning with ATT&CK technique T1071.004 (Application Layer Protocol: DNS) and T1566 (Phishing) as it enables attackers to craft malicious web pages that can harvest sensitive information from exposed storage systems.
Organizations should immediately upgrade to SeaweedFS version 4.30 or later where the vulnerability has been addressed through proper callback parameter validation, implementation of the X-Content-Type-Options: nosniff header, and enforcement of CORS restrictions on all JSON endpoints. Additional mitigations include implementing strict access controls through security.toml configuration files, enabling whitelist restrictions for exposed endpoints, binding services to specific interfaces rather than 0.0.0.0, and monitoring network traffic for suspicious requests to these vulnerable endpoints. Security teams should also consider implementing web application firewalls or reverse proxies with appropriate CORS policies to provide additional protection layers against similar vulnerabilities in other applications within their infrastructure.