Technical impact
An unauthenticated attacker who controls a registry or OCI‑layout blob source can supply blob data that does not match the claimed digest. When BuildKit receives such a blob through the low‑level LLB API, it stores the content under the reported digest, creating a snapshot that satisfies subsequent builds. The later victim build reuses this cached snapshot, allowing an attacker to inject arbitrary content into a so‑called shipping image without authentication or authorization. The weakness is a violation of integrity guarantees, represented by CWE‑354. This flaw can undermine the reliability of CI/CD pipelines because the consumer cannot rely on the authenticity of cached layers.
Affected Systems
The affected component is the Moby BuildKit product, specifically its low‑level LLB API that handles direct blob access from registries. Any BuildKit installation that uses this API to pull arbitrary OCI blobs is impacted. The issue cannot be exercised through ordinary Dockerfile builds and is confined to API‑level interactions. Affected‑version information is not available.
Risk and Exploitability
The CVSS score of 5.9 indicates moderate likelihood of exploitation but not trivial. The EPSS score for this vulnerability is not available, so the current exploitation probability is unknown. It is not listed in the CISA KEV catalog. An attacker controls a registry or blob source, which is often possible in internal or misconfigured environments. Because the flaw resides in the cache layer, successful exploitation requires that the attacker can submit crafted blobs and that a later build fetches the cached result. The primary attack vector is through untrusted blob sources accessed via the LLB API.
