When response caching is enabled (CACHE_ENABLED=true), the cache-key derivation in api/src/utils/get-cache-key.ts includes only version, path, query, and accountability.user (plus a conditional ip). Authorization context beyond user (share, role, roles, admin, app, policies) is not part of the key.
For share tokens this is load-bearing. Directus's share-authentication flow (api/src/services/shares.ts:100-105) issues a JWT without an id claim, so api/src/utils/get-accountability-for-token.ts never assigns accountability.user, leaving it null (the default from create-default-accountability.ts). Every share token, and every anonymous request, therefore reduces to user: null in the cache-key input. Two different shares (or an anonymous request and a share token) requesting the same URL with the same query produce identical cache keys. The first request populates the bucket with a permission-filtered response; subsequent hits from unrelated shares or anonymous clients receive that payload without any permission re-evaluation.
This is the web-cache pattern "authorization-dependent response cached under an unsegmented key" (cache key collision / missing authorization context in cache key, CWE-524 and CWE-639). Two adjacent read populations collide:
Share A populates the cache, Share B reads Share A's scoped response.CACHE_ENABLED=true (any store: memory, redis, memcached) plus at least one active directus_shares row. This is not a default-on bug: CACHE_ENABLED ships as false. The cache is documented as a production performance setting, so operators who enable it are the ones affected.12.0.0Exploitability
AV:NAC:LPR:NUI:NScope
S:CImpact
C:HI:NA:N8.6/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N