An OCI image manifest is the standard metadata record for a container image. It lists the image’s configuration object and the layer blobs that make up the filesystem, usually by digest. In practice, the manifest tells a registry and runtime exactly which content belongs to a given image version.
This matters because security tools use the manifest to verify what will run. Defenders compare manifests, digests, and signatures to detect tampering, drift, or unexpected rebuilds. Attackers may try to swap a mutable tag, publish a lookalike image, or alter referenced layers so a deployment pulls different content than intended. Pinning digests, checking signatures, and scanning the manifest-linked layers help ensure the image is the one that was built, reviewed, and approved.