Distribution: Client `manifests.Get()` does not verify returned content against requested digest

{
  "id": "8f3b663eae8d3dce43d46430dd016f0cc49fe07194fdb1e90066662a49414676",
  "url": "https://osv.dev/vulnerability/GHSA-685w-q87j-wqw3",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Distribution: Client `manifests.Get()` does not verify returned content against requested digest",
    "summary": "### Summary `registry/client.(*manifests).Get(ctx, dgst, …)` fetches a manifest by digest but never hashes the returned body and compares it against the requested digest. A malicious or compromised registry, or any MITM on the registry connection, can serve arbitrary manifest bytes in response to a digest-pinned request and the client returns the substituted content transparently to the caller. Any application relying on digest pinning for supply-chain integrity — image policy controllers, mirrors, pull-through caches — is silently undermined. The bundled pull-through proxy (`registry/proxy/proxymanifeststore.go`) is itself an unguarded consumer and is directly exploitable. ### Details **Root cause:** `registry/client/repository.go:488-505` reads the response body and passes it directly to `distribution.UnmarshalManifest` without ever computing `digest.FromBytes(body)` and comparing against the caller-supplied `dgst`. The `Docker-Content-Digest` response header is parsed (lines 251-292 in `descriptorFromResponse`) only to populate an out-parameter (`ReturnContentDigest`) and is itself server-supplied — it is never recomputed from the body, so a lying server can set it to whatever value the caller requested while delivering different bytes. **Attack path:** An attacker who controls the registry endpoint (malicious registry, compromised upstream, DNS hijack, or TLS MITM) responds to `GET /v2/{name}/manifests/{digest}` with: 1. `Docker-Content-Digest: ` (forged header) 2. A body",
    "evidence": "osv:GHSA-685w-q87j-wqw3",
    "products": [
      {
        "name": {
          "value": "github.com/docker/distribution",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "github.com/distribution/distribution/v3",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "3.1.2",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "GHSA-685w-q87j-wqw3",
      "aliases": [
        "BIT-distribution-2026-85747",
        "CVE-2026-85747",
        "GHSA-685w-q87j-wqw3"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "2.8.3"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/docker/distribution",
            "purl": "pkg:golang/github.com/docker/distribution",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-685w-q87j-wqw3/GHSA-685w-q87j-wqw3.json"
          }
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "3.1.2"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/distribution/distribution/v3",
            "purl": "pkg:golang/github.com/distribution/distribution/v3",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-685w-q87j-wqw3/GHSA-685w-q87j-wqw3.json"
          }
        }
      ],
      "modified": "2026-10-20T10:41:04.049860645Z",
      "provider": "osv",
      "references": [
        "https://github.com/distribution/distribution/security/advisories/GHSA-685w-q87j-wqw3",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-85747",
        "https://github.com/distribution/distribution/commit/8f91c26c8888a95a36c2357a6e30bc15d4dd76d3",
        "https://github.com/distribution/distribution/commit/960439b09f342cdeb8f1c0e18e8c7349bdcfbf80",
        "https://github.com/distribution/distribution",
        "https://github.com/distribution/distribution/releases/tag/v3.1.2"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-354"
        ],
        "severity": "MODERATE",
        "github_reviewed": true,
        "nvd_published_at": "2026-10-13T19:21:02Z",
        "github_reviewed_at": "2026-10-15T20:22:02Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-85747",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 379196,
  "published_at": "2026-10-15T20:22:02+00:00"
}