A flaw was found in Quay where the robot account listing function constructs a SQL LIKE pattern from user-controlled namespace names without escaping wildcard metacharacters. An attacker who creates a namespace containing an underscore character can match and retrieve robot accounts and their decrypted authentication tokens from other tenants' namespaces, leading to cross-tenant credential theft and unauthorized image operations.
Update to the fixed Red Hat Quay release for your version: 3.9.28, 3.10.28, 3.12.24, 3.14.10, 3.15.9, 3.16.7, 3.17.7, or 3.18.3. Red Hat has already fixed Quay.io. There is no other complete workaround.
If you cannot update immediately, restrict who can create organizations or namespaces containing an underscore, rotate robot tokens for any namespace that collides with an underscore-containing one, and monitor registry activity for pulls or pushes that don't match expected robot usage. These steps reduce exposure but do not fix the underlying flaw.