Summary
Better Call routing bug can lead to Cache Deception
Using 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.
Details
The 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.
The problematic code here:
const processRequest = async (request: Request) => {
const url = new URL(request.url);
const path = config?.basePath ? url.pathname.split(config.basePath)[1] : url.pathname;
Since this library is largely coupled with better-auth, it becomes more clear why this can be dangerous with an example request:
Impact
This is a cache deception vulnerability affecting better-call users with CDN caching enabled. which can expose sensitive data.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is GHSA-HQ75-XG7R-RX6C? GHSA-HQ75-XG7R-RX6C is a medium-severity security vulnerability in better-call (npm), affecting versions < 1.0.12. It is fixed in 1.0.12.
- Which versions of better-call are affected by GHSA-HQ75-XG7R-RX6C? better-call (npm) versions < 1.0.12 is affected.
- Is there a fix for GHSA-HQ75-XG7R-RX6C? Yes. GHSA-HQ75-XG7R-RX6C is fixed in 1.0.12. Upgrade to this version or later.
- Is GHSA-HQ75-XG7R-RX6C exploitable, and should I be worried? Whether GHSA-HQ75-XG7R-RX6C is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-HQ75-XG7R-RX6C is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-HQ75-XG7R-RX6C? Upgrade
better-callto 1.0.12 or later.