{"id":"GHSA-hq75-xg7r-rx6c","aliases":[],"url":"https://o3.security/vulnerability/GHSA-hq75-xg7r-rx6c","summary":"Better Call routing bug can lead to Cache Deception","details":"### Summary\n\nUsing a CDN that caches (`/**/*.png`, `/**/*.json`, `/**/*.css`, etc...) requests, a cache deception can emerge. This could lead to unauthorized access to user sessions and personal data when cached responses are served to other users.\n\n### Details\n\nThe vulnerability occurs in the request processing logic where path sanitization is insufficient. The library splits the path using `config.basePath` but doesn't properly validate the remaining path components. This allows specially crafted requests that appear to be static assets (like `/api/auth/get-session/api/auth/image.png` assuming `config.basePath`=`/api/auth`) to bypass typical CDN cache exclusion rules while actually returning sensitive data.\n\nThe problematic code [here](https://github.com/Bekacru/better-call/blob/8b6f13e24fad7f4666a582601517bb3232d4f4af/src/router.ts#L124):\n```js\n\tconst processRequest = async (request: Request) => {\n\t\tconst url = new URL(request.url);\n\t\tconst path = config?.basePath ? url.pathname.split(config.basePath)[1] : url.pathname;\n```\n\nSince this library is largely coupled with `better-auth`, it becomes more clear why this can be dangerous with an example request:\n\n<img width=\"800\" alt=\"image\" src=\"https://github.com/user-attachments/assets/2ab7c4dd-0700-4f59-863f-79f2b5edbb37\" />\n\n### Impact\n\nThis is a cache deception vulnerability affecting `better-call` users with CDN caching enabled. which can expose sensitive data.","published":"2025-07-11T17:09:53Z","modified":"2025-07-11T17:09:53Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"better-call","fixedVersion":"1.0.12"}],"fix":{"url":"https://github.com/Bekacru/better-call/commit/7c7d31b","label":"Bekacru/better-call@7c7d31b"},"references":[{"type":"WEB","url":"https://github.com/Bekacru/better-call/security/advisories/GHSA-hq75-xg7r-rx6c"},{"type":"WEB","url":"https://github.com/Bekacru/better-call/commit/7c7d31b"},{"type":"PACKAGE","url":"https://github.com/Bekacru/better-call"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2025-07-11T17:09:53Z"}}