{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","favicon":"https://feed.craftedsignal.io/favicon-32x32.png","feed_url":"https://feed.craftedsignal.io/products/starlette--1.0.1/feed.json","home_page_url":"https://feed.craftedsignal.io/","icon":"https://feed.craftedsignal.io/apple-touch-icon.png","items":[{"_cs_actors":[],"_cs_cpes":["cpe:2.3:a:encode:starlette:*:*:*:*:*:python:*:*"],"_cs_cves":[{"cvss":6.5,"id":"CVE-2026-48710"}],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["Starlette framework (\u003c 1.0.1)","FastAPI (\u003c 1.0.1)","vLLM (\u003c 1.0.1)","LiteLLM (\u003c 1.0.1)","Starlette (\u003c 1.0.1)"],"_cs_severities":["high"],"_cs_tags":["authentication bypass","web application","asgi"],"_cs_type":"advisory","_cs_vendors":["Kludex"],"content_html":"\u003cp\u003eThe \u0026quot;BadHost\u0026quot; vulnerability, tracked as CVE-2026-48710, impacts the Starlette framework (versions prior to 1.0.1), a widely used ASGI implementation underpinning numerous AI agents and tools. This framework serves as the base for FastAPI, vLLM, LiteLLM, and thousands of other open-source projects. The vulnerability stems from a lack of input sanitization on host header paths, allowing attackers to bypass authentication mechanisms. Given the widespread adoption of Starlette and the relative ease of exploitation, this vulnerability presents a significant risk, potentially leading to the exposure of sensitive data, credential theft (including third-party accounts), and supply chain attacks.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eThe attacker sends a crafted HTTP request to a Starlette-based application.\u003c/li\u003e\n\u003cli\u003eThe attacker manipulates the Host header in the HTTP request to include malicious characters or unexpected paths.\u003c/li\u003e\n\u003cli\u003eDue to missing sanitization, Starlette reconstructs the \u003ccode\u003erequest.url\u003c/code\u003e based on the malformed Host header.\u003c/li\u003e\n\u003cli\u003eThe reconstructed \u003ccode\u003erequest.url.path\u003c/code\u003e differs from the intended path based on the raw HTTP path.\u003c/li\u003e\n\u003cli\u003eAuthentication middleware or endpoint security checks relying on \u003ccode\u003erequest.url\u003c/code\u003e are bypassed.\u003c/li\u003e\n\u003cli\u003eThe attacker gains unauthorized access to sensitive data or restricted functionality.\u003c/li\u003e\n\u003cli\u003eThe attacker may exfiltrate stolen credentials for third-party accounts stored in MCP servers.\u003c/li\u003e\n\u003cli\u003eThe attacker leverages compromised credentials for supply chain attacks.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eThe BadHost vulnerability (CVE-2026-48710) affects millions of servers utilizing the Starlette framework and related projects. Successful exploitation can lead to authentication bypass, allowing attackers to access sensitive data, steal credentials, and potentially launch supply chain attacks. The targeted sectors are broad due to the widespread adoption of Starlette in building various applications, including AI agents, web services, and management UIs. The vulnerability can expose credentials for third-party accounts stored in MCP servers, further amplifying the potential damage.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eApply the patch to upgrade Starlette to version 1.0.1 or later to address CVE-2026-48710 immediately after thorough testing.\u003c/li\u003e\n\u003cli\u003eDeploy a reverse proxy in front of your ASGI server to validate and normalize the Host header before forwarding requests, mitigating the attack vector.\u003c/li\u003e\n\u003cli\u003eIf using middleware, utilize \u003ccode\u003escope[\u0026quot;path\u0026quot;]\u003c/code\u003e instead of \u003ccode\u003erequest.url.path\u003c/code\u003e to avoid relying on the reconstructed URL, as recommended in the advisory.\u003c/li\u003e\n\u003cli\u003eMonitor web server logs for suspicious Host header manipulations and unusual request patterns to detect potential exploitation attempts using the provided Sigma rule.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-09-02T17:56:10Z","date_published":"2026-05-28T16:32:49Z","id":"https://feed.craftedsignal.io/briefs/2026-05-starlette-auth-bypass/","summary":"CVE-2026-48710, also known as BadHost, is an authentication bypass vulnerability affecting the Starlette framework before version 1.0.1, and related frameworks like FastAPI, vLLM, and LiteLLM, due to a lack of input sanitization on host header paths, potentially allowing attackers to access sensitive data and steal credentials.","title":"Starlette Framework Authentication Bypass Vulnerability (CVE-2026-48710)","url":"https://feed.craftedsignal.io/briefs/2026-05-starlette-auth-bypass/"}],"language":"en","title":"CraftedSignal Threat Feed - Starlette (\u003c 1.0.1)","version":"https://jsonfeed.org/version/1.1"}