CVE-2026-55588: ORAS CLI: Cyclic Referrer Graph Can Cause Unbounded Recursion and Resource Consumption

A malicious OCI registry can return a cyclic referrer graph (e.g. A -> A or A -> B -> A). The ORAS CLI’s recursive referrer traversal does not track visited descriptors, so a cycle causes unbounded recursion and memory growth — a client-side denial of service.

This affects oras discover (recursive referrer traversal) and the recursive referrer counting used by oras backup and oras restore. Because oras discover --depth defaults to 0 (unlimited), discover is affected out of the box.

Note: This advisory covers only the ORAS CLI (oras.land/oras). The related Referrers API pagination loop in the oras-go library is tracked in a separate advisory on the oras-go repository.