From 15019ad0f9aff96f1fe25e253a75c674b4892491 Mon Sep 17 00:00:00 2001
From: Massimiliano Ferrero <m.ferrero@cognitio.it>
Date: Sat, 20 Jun 2026 14:26:22 +0200
Subject: [PATCH] fix: reject manifest PUT whose digest reference does not
 match the content

A reference containing ":" addresses a manifest by digest; the submitted content must hash to
exactly that digest. Previously a mismatched or malformed digest reference was stored as a tag
under the wrong key (the content checksum still matched), returning 201 instead of 400. Now returns
400 DIGEST_INVALID. Adds regression tests (mismatched digest, malformed digest, correct digest).
---
 src/errors.ts      |  8 ++++++-
 src/registry/r2.ts | 11 ++++++++++
 test/index.test.ts | 52 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/src/errors.ts b/src/errors.ts
index 95e655f..0508415 100644
--- a/src/errors.ts
+++ b/src/errors.ts
@@ -72,7 +72,13 @@ export class InternalError extends Response {
 
 export class ManifestError extends Response {
   constructor(
-    code: "MANIFEST_INVALID" | "BLOB_UNKNOWN" | "MANIFEST_UNVERIFIED" | "TAG_INVALID" | "NAME_INVALID",
+    code:
+      | "MANIFEST_INVALID"
+      | "BLOB_UNKNOWN"
+      | "MANIFEST_UNVERIFIED"
+      | "TAG_INVALID"
+      | "NAME_INVALID"
+      | "DIGEST_INVALID",
     message: string,
     detail: Record<string, string> = {},
   ) {
diff --git a/src/registry/r2.ts b/src/registry/r2.ts
index 7f01098..5ea8f46 100644
--- a/src/registry/r2.ts
+++ b/src/registry/r2.ts
@@ -509,6 +509,17 @@ export class R2Registry implements Registry {
     shaWriter.close();
     const digest = await sha256.digest;
     const digestStr = hexToDigest(digest);
+
+    // A reference containing ":" addresses the manifest by digest (an OCI tag never contains ":").
+    // The submitted content must hash to exactly that digest; a mismatched or malformed digest
+    // reference is a client error (400 DIGEST_INVALID), not a tag to store under the wrong key.
+    if (reference.includes(":") && reference !== digestStr) {
+      const message = isValidDigest(reference)
+        ? `provided digest ${reference} does not match content digest ${digestStr}`
+        : `invalid digest reference ${reference}`;
+      return { response: new ManifestError("DIGEST_INVALID", message) };
+    }
+
     const text = await blob.text();
     let manifestJSON: unknown;
     try {
diff --git a/test/index.test.ts b/test/index.test.ts
index 65ebe53..51a7a0b 100644
--- a/test/index.test.ts
+++ b/test/index.test.ts
@@ -2380,3 +2380,55 @@ test("docker.io", () => {
     }
   }
 });
+
+describe("manifest PUT digest validation", () => {
+  test("PUT manifest by a mismatched digest is rejected 400 DIGEST_INVALID (not stored)", async () => {
+    const name = "manifestdigest/mismatch";
+    const manifest = await generateManifest(name);
+    const data = JSON.stringify(manifest);
+    const wrongDigest = "sha256:" + "0".repeat(64);
+    const res = await fetch(
+      createRequest("PUT", `/v2/${name}/manifests/${wrongDigest}`, new Blob([data]).stream(), {
+        "Content-Type": "application/vnd.oci.image.manifest.v1+json",
+      }),
+    );
+    expect(res.status).toBe(400);
+    const body = (await res.json()) as { errors: { code: string }[] };
+    expect(body.errors[0].code).toBe("DIGEST_INVALID");
+    // Must NOT have been stored under the wrong digest key.
+    const get = await fetch(createRequest("GET", `/v2/${name}/manifests/${wrongDigest}`, null));
+    expect(get.status).toBe(404);
+  });
+
+  test("PUT manifest by a malformed digest reference is rejected 400 DIGEST_INVALID", async () => {
+    const name = "manifestdigest/malformed";
+    const manifest = await generateManifest(name);
+    const res = await fetch(
+      createRequest(
+        "PUT",
+        `/v2/${name}/manifests/sha256:baddigeststring`,
+        new Blob([JSON.stringify(manifest)]).stream(),
+        {
+          "Content-Type": "application/vnd.oci.image.manifest.v1+json",
+        },
+      ),
+    );
+    expect(res.status).toBe(400);
+    const body = (await res.json()) as { errors: { code: string }[] };
+    expect(body.errors[0].code).toBe("DIGEST_INVALID");
+  });
+
+  test("PUT manifest by its correct digest still succeeds (201)", async () => {
+    const name = "manifestdigest/correct";
+    const manifest = await generateManifest(name);
+    const data = JSON.stringify(manifest);
+    const digest = await getSHA256(data);
+    const res = await fetch(
+      createRequest("PUT", `/v2/${name}/manifests/${digest}`, new Blob([data]).stream(), {
+        "Content-Type": "application/vnd.oci.image.manifest.v1+json",
+      }),
+    );
+    expect(res.status).toBe(201);
+    expect(res.headers.get("docker-content-digest")).toEqual(digest);
+  });
+});