Uber Kraken through 0.1.29 fails to validate the tag parameter in the /tags/{tag} endpoint, allowing unauthenticated attackers to traverse outside the configured storage root. Attackers can use percent-encoded parent-directory segments in the tag parameter to read arbitrary files accessible to the testfs backend process.

Kraken agents fail to verify peer-to-peer downloaded blobs against their requested SHA-256 digest before committing to the content-addressable cache, relying only on CRC32 checksums for piece validation. Attackers on the agent-to-agent path or malicious peers can supply substituted content with forged CRC32 corrections that passes per-piece checks, poisoning the cache with attacker-chosen container image layers or manifests that are re-seeded and executed by other hosts.