{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/products/github-mcp-server--1.1.0/feed.json","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cpes":[],"_cs_cves":[],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["github-mcp-server (\u003c 1.1.0)"],"_cs_severities":["medium"],"_cs_tags":["denial-of-service","vulnerability","github"],"_cs_type":"advisory","_cs_vendors":["GitHub"],"content_html":"\u003cp\u003eA high-severity denial-of-service vulnerability, identified as CVE-2026-47427, has been discovered in the GitHub MCP Server. This flaw, specifically a nil pointer dereference, resides within the \u003ccode\u003eCompletionsHandler\u003c/code\u003e function (located at \u003ccode\u003epkg/github/server.go:198\u003c/code\u003e) which is responsible for processing \u003ccode\u003ecompletion/complete\u003c/code\u003e JSON-RPC requests. Attackers can exploit this vulnerability without authentication by sending a crafted JSON-RPC message that either contains empty \u003ccode\u003eparams\u003c/code\u003e or is missing the crucial \u003ccode\u003eref\u003c/code\u003e field within the \u003ccode\u003eparams\u003c/code\u003e. Upon receiving such a request, the server attempts to dereference a \u003ccode\u003enil\u003c/code\u003e pointer, causing the Go runtime to panic and the MCP Server process to crash entirely. This vulnerability affects GitHub MCP Server versions prior to 1.1.0 and allows for a complete and unrecoverable denial of service by any unauthenticated client capable of sending JSON-RPC messages.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAn unauthenticated attacker identifies a GitHub MCP Server instance accessible on the network.\u003c/li\u003e\n\u003cli\u003eThe attacker establishes a connection and completes the necessary MCP initialization handshake with the server.\u003c/li\u003e\n\u003cli\u003eThe attacker crafts a malformed JSON-RPC \u003ccode\u003ecompletion/complete\u003c/code\u003e request, intentionally omitting or emptying the \u003ccode\u003eref\u003c/code\u003e parameter within the \u003ccode\u003eparams\u003c/code\u003e object (e.g., \u003ccode\u003e{\u0026quot;jsonrpc\u0026quot;:\u0026quot;2.0\u0026quot;,\u0026quot;id\u0026quot;:2,\u0026quot;method\u0026quot;:\u0026quot;completion/complete\u0026quot;,\u0026quot;params\u0026quot;:{}}\u003c/code\u003e).\u003c/li\u003e\n\u003cli\u003eThe attacker sends this crafted request to the vulnerable \u003ccode\u003e/completion/complete\u003c/code\u003e endpoint on the GitHub MCP Server.\u003c/li\u003e\n\u003cli\u003eThe server's \u003ccode\u003eCompletionsHandler\u003c/code\u003e function receives the request and attempts to access \u003ccode\u003eparams.Ref\u003c/code\u003e without first verifying if \u003ccode\u003eparams\u003c/code\u003e or \u003ccode\u003eparams.Ref\u003c/code\u003e is \u003ccode\u003enil\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eDue to the malformed request, \u003ccode\u003eparams.Ref\u003c/code\u003e is \u003ccode\u003enil\u003c/code\u003e at the point of access, leading to a nil pointer dereference.\u003c/li\u003e\n\u003cli\u003eThe Go runtime detects the invalid memory access and triggers an immediate panic.\u003c/li\u003e\n\u003cli\u003eThe GitHub MCP Server process crashes, resulting in a complete and unrecoverable denial of service for all connected clients.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eThe successful exploitation of CVE-2026-47427 leads to an immediate and complete denial of service for the GitHub MCP Server. Any unauthenticated client capable of sending JSON-RPC messages can crash the server, making it unavailable to legitimate users. The panic caused by the nil pointer dereference is unrecoverable and terminates the server process, requiring manual intervention to restart. Automated fuzzing efforts demonstrated a significant crash rate (11.7% of test cases), indicating the ease with which this vulnerability can be triggered. Organizations using affected versions of GitHub MCP Server are at risk of significant service disruption and availability loss.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003ePatch affected GitHub MCP Server instances to version 1.1.0 or newer immediately to mitigate CVE-2026-47427.\u003c/li\u003e\n\u003cli\u003eConfigure webserver or API gateway logs to capture full request bodies for the \u003ccode\u003e/completion/complete\u003c/code\u003e endpoint to enable detection of malformed JSON-RPC requests as described in the attack chain.\u003c/li\u003e\n\u003cli\u003eDeploy a Web Application Firewall (WAF) or API gateway capable of inspecting and blocking malformed JSON-RPC requests targeting the \u003ccode\u003e/completion/complete\u003c/code\u003e endpoint, specifically looking for empty or missing \u003ccode\u003eref\u003c/code\u003e parameters.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-07-28T14:38:36Z","date_published":"2026-07-28T14:38:36Z","id":"https://feed.craftedsignal.io/briefs/2026-07-github-mcp-server-dos/","summary":"A nil pointer dereference vulnerability, tracked as CVE-2026-47427, in the GitHub MCP Server's `completion/complete` handler allows an unauthenticated attacker to cause a complete denial of service by sending a malformed JSON-RPC request with missing or empty parameters for the `ref` field, leading to an immediate server crash.","title":"GitHub MCP Server Nil Pointer Dereference DoS in completion/complete Handler (CVE-2026-47427)","url":"https://feed.craftedsignal.io/briefs/2026-07-github-mcp-server-dos/"}],"language":"en","title":"CraftedSignal Threat Feed - Github-Mcp-Server (\u003c 1.1.0)","version":"https://jsonfeed.org/version/1.1"}