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Medium, CVSS 4.9amended

Better Call routing bug can lead to Cache Deception

GHSA-hq75-xg7r-rx6c

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (better-call 1.0.12), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
4.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U · score source
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

Summary 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: Since this library is largely coupled with better-auth, it becomes more clear why this can be dangerous with an example request: <img width="800" alt="image" src="https://github.com/user-attachments/assets/2ab7c4dd-0700-4f59-863f-79f2b5edbb37" / Impact This is a cache deception…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-hq75-xg7r-rx6c

  2. Revision 2 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 1 · created ·

    Published from osv record GHSA-hq75-xg7r-rx6c

Agent brief

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# Patch Next advisory brief: GHSA-hq75-xg7r-rx6c

Advisory: Better Call routing bug can lead to Cache Deception
IDs: GHSA-hq75-xg7r-rx6c
Record: https://patchnext.com/advisories/ghsa-hq75-xg7r-rx6c (revision 3, source checked 26 Oct 2026, 12:37 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: better-call 1.0.12. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm better-call: affected < 1.0.12; fixed in 1.0.12

## Suggested inspection (read-only)
- `npm ls better-call --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on better-call.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-hq75-xg7r-rx6c (OSV record GHSA-hq75-xg7r-rx6c lists affected ranges: npm better-call >=0 <1.0.12 (fixed))
- Verified: https://github.com/advisories/GHSA-hq75-xg7r-rx6c (GitHub-reviewed advisory GHSA-hq75-xg7r-rx6c lists affected ranges: npm better-call >=0 <1.0.12)

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