Executive brief
etcd is a distributed key-value database used to store critical configuration and state for distributed systems like Kubernetes. A flaw in the authentication checks allows a user with read permission for a single key to view all data lexicographically after that key, effectively bypassing access controls in authenticated clusters.
Technical details
An authorization bypass vulnerability exists in the Watch gRPC API (server/etcdserver/api/v3rpc/watch.go) where an open-ended RangeEnd sentinel is rewritten before the RBAC permission check in server/auth/range_perm_cache.go function isRangeOpPermitted. This causes range-based watch requests using clientv3.WithFromKey() to bypass permission checks and be treated as exact-key watches, allowing attackers with READ permission on one key to receive watch events for all keys lexicographically greater than or equal to that key. The vulnerability requires authentication to be enabled on the cluster and affects only the Watch API; Range/Get and DeleteRange operations are unaffected. Fixed in versions 3.5.33, 3.6.14, and 3.7.1.
Affected products
- etcd etcd before 3.5.33, 3.6.14, and 3.7.1
Timeline
- 2026-08-12: disclosed: Public disclosure via NVD
- 2026-08-12: patched: Fixed in versions 3.5.33, 3.6.14, and 3.7.1