diff --git a/README.md b/README.md
index dd32b4ad0..34ddc3216 100644
--- a/README.md
+++ b/README.md
@@ -349,6 +349,19 @@ same major line. Should you need to upgrade to a new major, use an explicit
   environment variables are required and as plain text. If you want to send an
   empty password, explicitly set `COREPACK_NPM_PASSWORD` to an empty string.
 
+- `COREPACK_ON_UNVERIFIED_DOWNLOAD` can be set to:
+  - `warn` (case insensitive): attempting to download an unsigned version without
+    providing a hash will emit a warning to stderr.
+  - `error` (case insensitive): attempting to download an unsigned version without
+    providing a hash will fail with an error, and nothing gets downloaded.
+  - `strict-warn` (case insensitive): same as `warn`, and additionally emits a
+    warning when downloading a version that is not pinned by a hash, even when
+    its signature can be verified.
+  - `strict-error` (case insensitive): same as `error`, and additionally fails
+    when downloading a version that is not pinned by a hash, even when its
+    signature can be verified.
+  - `ignore` (or any other unsupported value): disables that security feature.
+
 - `HTTP_PROXY`, `HTTPS_PROXY`, and `NO_PROXY` are supported through
   [`NODE_USE_ENV_PROXY=1`](https://nodejs.org/api/cli.html#node_use_env_proxy1).
 
diff --git a/sources/corepackUtils.ts b/sources/corepackUtils.ts
index e80b43150..d38df1c7b 100644
--- a/sources/corepackUtils.ts
+++ b/sources/corepackUtils.ts
@@ -231,6 +231,31 @@ export async function installVersion(installTarget: string, locator: Locator, {s
     }
   }
 
+  const registry = getRegistryFromPackageManagerSpec(spec);
+  const canVerifySignature = registry.type === `npm` && !registry.bin && !shouldSkipIntegrityCheck();
+  if (!build[1]) {
+    const {COREPACK_ON_UNVERIFIED_DOWNLOAD} = process.env;
+    debugUtils.log(`No hash provided${canVerifySignature ? `` : `, and signature cannot be verified`}; checking COREPACK_ON_UNVERIFIED_DOWNLOAD, set to: ${COREPACK_ON_UNVERIFIED_DOWNLOAD}`);
+    const mode = COREPACK_ON_UNVERIFIED_DOWNLOAD?.toUpperCase();
+    // In strict mode, a hash is required even when the signature can be verified.
+    const isStrict = mode === `STRICT-ERROR` || mode === `STRICT-WARN`;
+    if (isStrict || !canVerifySignature) {
+      const reason = canVerifySignature
+        ? `is not pinned by a hash`
+        : `could not be verified`;
+
+      switch (mode) {
+        case `ERROR`:
+        case `STRICT-ERROR`:
+          throw new Error(`Integrity of ${locator.name}@${version} ${reason}. Downloading unverified versions is disabled by the COREPACK_ON_UNVERIFIED_DOWNLOAD env variable. Please provide a hash.`);
+
+        case `WARN`:
+        case `STRICT-WARN`:
+          console.warn(`Integrity of ${locator.name}@${version} ${reason}. Consider providing a hash. Set COREPACK_ON_UNVERIFIED_DOWNLOAD to 'ignore' to remove this warning.`);
+      }
+    }
+  }
+
   let url: string;
   let signatures: Array<{keyid: string, sig: string}>;
   let integrity: string;
@@ -238,7 +263,6 @@ export async function installVersion(installTarget: string, locator: Locator, {s
   if (locatorIsASupportedPackageManager) {
     url = spec.url.replace(`{}`, version);
     if (process.env.COREPACK_NPM_REGISTRY) {
-      const registry = getRegistryFromPackageManagerSpec(spec);
       if (registry.type === `npm`) {
         ({tarball: url, signatures, integrity} = await npmRegistryUtils.fetchTarballURLAndSignature(registry.package, version));
         if (registry.bin) {
@@ -294,19 +318,18 @@ export async function installVersion(installTarget: string, locator: Locator, {s
     }
   }
 
-  if (!build[1]) {
-    const registry = getRegistryFromPackageManagerSpec(spec);
-    if (registry.type === `npm` && !registry.bin && !shouldSkipIntegrityCheck()) {
-      if (signatures! == null || integrity! == null)
-        ({signatures, integrity} = (await npmRegistryUtils.fetchTarballURLAndSignature(registry.package, version)));
-
-      await npmRegistryUtils.verifySignature({signatures, integrity, packageName: registry.package, version});
-      // @ts-expect-error ignore readonly
-      build[1] = Buffer.from(integrity.slice(`sha512-`.length), `base64`).toString(`hex`);
-    }
+  if (!build[1] && canVerifySignature && registry.type === `npm`) {
+    if (signatures! == null || integrity! == null)
+      ({signatures, integrity} = (await npmRegistryUtils.fetchTarballURLAndSignature(registry.package, version)));
+
+    npmRegistryUtils.verifySignature({signatures, integrity, packageName: registry.package, version});
+    // @ts-expect-error ignore readonly
+    build[1] = Buffer.from(integrity.slice(`sha512-`.length), `base64`).toString(`hex`);
   }
-  if (build[1] && actualHash !== build[1])
+  if (build[1] && actualHash !== build[1]) {
+    await fs.promises.rm(tmpFolder, {recursive: true, force: true});
     throw new Error(`Mismatch hashes. Expected ${build[1]}, got ${actualHash}`);
+  }
 
   const serializedHash = `${algo}.${actualHash}`;
 
diff --git a/tests/Up.test.ts b/tests/Up.test.ts
index 1934202b9..5ccbfb22a 100644
--- a/tests/Up.test.ts
+++ b/tests/Up.test.ts
@@ -24,9 +24,11 @@ describe(`UpCommand`, () => {
           packageManager: `yarn@2.1.0`,
         });
 
+        process.env.COREPACK_ON_UNVERIFIED_DOWNLOAD = `warn`;
+
         await expect(runCli(cwd, [`up`])).resolves.toMatchObject({
           exitCode: 0,
-          stderr: ``,
+          stderr: `Integrity of yarn@2.4.3 could not be verified. Consider providing a hash. Set COREPACK_ON_UNVERIFIED_DOWNLOAD to 'ignore' to remove this warning.\n`,
           stdout: expect.stringMatching(/^Installing yarn@2\.4\.3 in the project\.\.\.\n\n/),
         });
 
diff --git a/tests/Use.test.ts b/tests/Use.test.ts
index 4010bf335..6dd37939e 100644
--- a/tests/Use.test.ts
+++ b/tests/Use.test.ts
@@ -136,9 +136,11 @@ describe(`UseCommand`, () => {
       const subfolder = ppath.join(cwd, `subfolder`);
       await xfs.mkdirPromise(subfolder);
 
+      process.env.COREPACK_ON_UNVERIFIED_DOWNLOAD = `warn`;
+
       await expect(runCli(subfolder, [`use`, `yarn@2.2.2`])).resolves.toMatchObject({
         exitCode: 0,
-        stderr: ``,
+        stderr: `Integrity of yarn@2.2.2 could not be verified. Consider providing a hash. Set COREPACK_ON_UNVERIFIED_DOWNLOAD to 'ignore' to remove this warning.\n`,
       });
       await expect(runCli(cwd, [`yarn`, `--version`])).resolves.toMatchObject({
         exitCode: 0,
diff --git a/tests/main.test.ts b/tests/main.test.ts
index e6f7d7200..e00086885 100644
--- a/tests/main.test.ts
+++ b/tests/main.test.ts
@@ -856,7 +856,7 @@ it(`should support disabling the network accesses from the environment`, async (
 
   await xfs.mktempPromise(async cwd => {
     await xfs.writeJsonPromise(ppath.join(cwd, `package.json` as Filename), {
-      packageManager: `yarn@2.2.2`,
+      packageManager: `yarn@2.2.2+sha1.9aede2626b101719cbc1314d61def0742852ba11`,
     });
 
     await expect(runCli(cwd, [`yarn`, `--version`])).resolves.toMatchObject({
@@ -881,12 +881,12 @@ describe(`read-only and offline environment`, () => {
 
       // Prepare fake project
       await xfs.writeJsonPromise(ppath.join(cwd, `package.json` as Filename), {
-        packageManager: `yarn@2.2.2`,
+        packageManager: `yarn@2.2.2+sha1.9aede2626b101719cbc1314d61def0742852ba11`,
       });
 
       // $ corepack install
       await expect(runCli(cwd, [`install`])).resolves.toMatchObject({
-        stdout: `Adding yarn@2.2.2 to the cache...\n`,
+        stdout: `Adding yarn@2.2.2+sha1.9aede2626b101719cbc1314d61def0742852ba11 to the cache...\n`,
         stderr: ``,
         exitCode: 0,
       });
@@ -1549,6 +1549,196 @@ describe(`should pick up COREPACK_INTEGRITY_KEYS from env`, () => {
   });
 });
 
+describe(`unverified downloads`, () => {
+  beforeEach(() => {
+    process.env.AUTH_TYPE = `COREPACK_NPM_TOKEN`; // See `_registryServer.mjs`
+    process.env.COREPACK_DEFAULT_TO_LATEST = `1`;
+    process.env.COREPACK_INTEGRITY_KEYS = `0`;
+  });
+
+  it(`from env variable`, async () => {
+    await xfs.mktempPromise(async cwd => {
+      await xfs.writeJsonPromise(ppath.join(cwd, `package.json` as Filename), {});
+
+      process.env.COREPACK_ON_UNVERIFIED_DOWNLOAD = `error`;
+      await expect(runCli(cwd, [`pnpm@1.x`, `--version`], true)).resolves.toMatchObject({
+        exitCode: 1,
+        stdout: ``,
+        stderr: expect.stringContaining(`Downloading unverified versions is disabled by the COREPACK_ON_UNVERIFIED_DOWNLOAD env variable`),
+      });
+      await expect(runCli(cwd, [`yarn@1.x`, `--version`], true)).resolves.toMatchObject({
+        exitCode: 1,
+        stdout: ``,
+        stderr: expect.stringContaining(`Downloading unverified versions is disabled by the COREPACK_ON_UNVERIFIED_DOWNLOAD env variable`),
+      });
+
+      process.env.COREPACK_ON_UNVERIFIED_DOWNLOAD = `ignore`;
+      await expect(runCli(cwd, [`yarn@1.x`, `--version`], true)).resolves.toMatchObject({
+        exitCode: 0,
+        stdout: `yarn: Hello from custom registry\n`,
+        stderr: ``, // No warning expected
+      });
+
+      process.env.COREPACK_ON_UNVERIFIED_DOWNLOAD = `warn`;
+      await expect(runCli(cwd, [`pnpm@1.x`, `--version`], true)).resolves.toMatchObject({
+        exitCode: 0,
+        stdout: `pnpm: Hello from custom registry\n`,
+        stderr: expect.stringContaining(`Integrity of pnpm@1.9998.9999 could not be verified.`),
+      });
+      await expect(runCli(cwd, [`yarn@1.x`, `--version`], true)).resolves.toMatchObject({
+        exitCode: 0,
+        stdout: `yarn: Hello from custom registry\n`,
+        stderr: ``, // Already cached, no warning expected
+      });
+    });
+  });
+
+  it(`from .corepack.env file`, async () => {
+    await xfs.mktempPromise(async cwd => {
+      await xfs.writeJsonPromise(ppath.join(cwd, `package.json` as Filename), {});
+
+      await xfs.writeFilePromise(ppath.join(cwd, `.corepack.env` as Filename), `COREPACK_ON_UNVERIFIED_DOWNLOAD=error\n`);
+      await expect(runCli(cwd, [`pnpm@1.x`, `--version`], true)).resolves.toMatchObject({
+        exitCode: 1,
+        stdout: ``,
+        stderr: expect.stringContaining(`Downloading unverified versions is disabled by the COREPACK_ON_UNVERIFIED_DOWNLOAD env variable`),
+      });
+      await expect(runCli(cwd, [`yarn@1.x`, `--version`], true)).resolves.toMatchObject({
+        exitCode: 1,
+        stdout: ``,
+        stderr: expect.stringContaining(`Downloading unverified versions is disabled by the COREPACK_ON_UNVERIFIED_DOWNLOAD env variable`),
+      });
+
+      await xfs.writeFilePromise(ppath.join(cwd, `.corepack.env` as Filename), `COREPACK_ON_UNVERIFIED_DOWNLOAD=ignore\n`);
+      await expect(runCli(cwd, [`yarn@1.x`, `--version`], true)).resolves.toMatchObject({
+        exitCode: 0,
+        stdout: `yarn: Hello from custom registry\n`,
+        stderr: ``, // No warning expected
+      });
+
+      await xfs.writeFilePromise(ppath.join(cwd, `.corepack.env` as Filename), `COREPACK_ON_UNVERIFIED_DOWNLOAD=warn\n`);
+      await expect(runCli(cwd, [`pnpm@1.x`, `--version`], true)).resolves.toMatchObject({
+        exitCode: 0,
+        stdout: `pnpm: Hello from custom registry\n`,
+        stderr: expect.stringContaining(`Integrity of pnpm@1.9998.9999 could not be verified.`),
+      });
+      await expect(runCli(cwd, [`yarn@1.x`, `--version`], true)).resolves.toMatchObject({
+        exitCode: 0,
+        stdout: `yarn: Hello from custom registry\n`,
+        stderr: ``, // Already cached, no warning expected
+      });
+    });
+  });
+
+  it(`from env file defined by COREPACK_ENV_FILE`, async () => {
+    await xfs.mktempPromise(async cwd => {
+      await xfs.writeJsonPromise(ppath.join(cwd, `package.json` as Filename), {
+      });
+
+      await xfs.writeFilePromise(ppath.join(cwd, `.corepack.env` as Filename), `COREPACK_ON_UNVERIFIED_DOWNLOAD=error\n`);
+      await xfs.writeFilePromise(ppath.join(cwd, `.other.env` as Filename), `COREPACK_ON_UNVERIFIED_DOWNLOAD=warn\n`);
+
+      // By default, Corepack should be using .corepack.env and fail.
+      await expect(runCli(cwd, [`pnpm@1.x`, `--version`], true)).resolves.toMatchObject({
+        exitCode: 1,
+        stdout: ``,
+        stderr: expect.stringContaining(`Downloading unverified versions is disabled by the COREPACK_ON_UNVERIFIED_DOWNLOAD env variable`),
+      });
+
+      process.env.COREPACK_ENV_FILE = `.other.env`;
+      await expect(runCli(cwd, [`pnpm@1.x`, `--version`], true)).resolves.toMatchObject({
+        exitCode: 0,
+        stdout: `pnpm: Hello from custom registry\n`,
+        stderr: expect.stringContaining(`Integrity of pnpm@1.9998.9999 could not be verified.`),
+      });
+    });
+  });
+
+  it(`from env even if there's a .corepack.env file`, async () => {
+    await xfs.mktempPromise(async cwd => {
+      await xfs.writeJsonPromise(ppath.join(cwd, `package.json` as Filename), {});
+
+      await xfs.writeFilePromise(ppath.join(cwd, `.corepack.env` as Filename), `COREPACK_ON_UNVERIFIED_DOWNLOAD=error\n`);
+
+      // By default, Corepack should be using .corepack.env (or the built-in ones on Node.js 18.x) and fail.
+      await expect(runCli(cwd, [`pnpm@1.x`, `--version`], true)).resolves.toMatchObject({
+        exitCode: 1,
+        stdout: ``,
+        stderr: expect.stringContaining(`Downloading unverified versions is disabled by the COREPACK_ON_UNVERIFIED_DOWNLOAD env variable`),
+      });
+
+      process.env.COREPACK_ON_UNVERIFIED_DOWNLOAD = `warn`;
+      await expect(runCli(cwd, [`pnpm@1.x`, `--version`], true)).resolves.toMatchObject({
+        exitCode: 0,
+        stdout: `pnpm: Hello from custom registry\n`,
+        stderr: expect.stringContaining(`Integrity of pnpm@1.9998.9999 could not be verified`),
+      });
+    });
+  });
+});
+
+describe(`downloads not pinned by a hash`, () => {
+  it(`should not warn in non-strict mode when the signature can be verified`, async () => {
+    await xfs.mktempPromise(async cwd => {
+      await xfs.writeJsonPromise(ppath.join(cwd, `package.json` as Filename), {
+        packageManager: `yarn@1.22.4`,
+      });
+
+      process.env.COREPACK_ON_UNVERIFIED_DOWNLOAD = `warn`;
+      await expect(runCli(cwd, [`yarn`, `--version`])).resolves.toMatchObject({
+        exitCode: 0,
+        stdout: `1.22.4\n`,
+        stderr: ``,
+      });
+    });
+  });
+
+  it(`should warn when COREPACK_ON_UNVERIFIED_DOWNLOAD is set to strict-warn`, async () => {
+    await xfs.mktempPromise(async cwd => {
+      await xfs.writeJsonPromise(ppath.join(cwd, `package.json` as Filename), {
+        packageManager: `yarn@1.22.4`,
+      });
+
+      process.env.COREPACK_ON_UNVERIFIED_DOWNLOAD = `strict-warn`;
+      await expect(runCli(cwd, [`yarn`, `--version`])).resolves.toMatchObject({
+        exitCode: 0,
+        stdout: `1.22.4\n`,
+        stderr: `Integrity of yarn@1.22.4 is not pinned by a hash. Consider providing a hash. Set COREPACK_ON_UNVERIFIED_DOWNLOAD to 'ignore' to remove this warning.\n`,
+      });
+    });
+  });
+
+  it(`should fail when COREPACK_ON_UNVERIFIED_DOWNLOAD is set to STRICT-ERROR`, async () => {
+    await xfs.mktempPromise(async cwd => {
+      await xfs.writeJsonPromise(ppath.join(cwd, `package.json` as Filename), {
+        packageManager: `yarn@1.22.4`,
+      });
+
+      process.env.COREPACK_ON_UNVERIFIED_DOWNLOAD = `STRICT-ERROR`;
+      await expect(runCli(cwd, [`yarn`, `--version`])).resolves.toMatchObject({
+        exitCode: 1,
+        stdout: ``,
+        stderr: expect.stringContaining(`Integrity of yarn@1.22.4 is not pinned by a hash. Downloading unverified versions is disabled by the COREPACK_ON_UNVERIFIED_DOWNLOAD env variable.`),
+      });
+    });
+  });
+
+  it(`should not interfere with versions pinned by a hash in strict mode`, async () => {
+    await xfs.mktempPromise(async cwd => {
+      await xfs.writeJsonPromise(ppath.join(cwd, `package.json` as Filename), {
+        packageManager: `yarn@1.22.4+sha224.0d6eecaf4d82ec12566fdd97143794d0f0c317e0d652bd4d1b305430`,
+      });
+
+      process.env.COREPACK_ON_UNVERIFIED_DOWNLOAD = `strict-error`;
+      await expect(runCli(cwd, [`yarn`, `--version`])).resolves.toMatchObject({
+        exitCode: 0,
+        stdout: `1.22.4\n`,
+        stderr: ``,
+      });
+    });
+  });
+});
+
 for (const authType of [`COREPACK_NPM_REGISTRY`, `COREPACK_NPM_TOKEN`, `COREPACK_NPM_PASSWORD`, `PROXY`]) {
   describe(`custom registry with auth ${authType}`, () => {
     beforeEach(() => {
@@ -1741,8 +1931,8 @@ describe(`handle integrity checks`, () => {
       });
       await expect(runCli(cwd, [`use`, `pnpm`], true)).resolves.toMatchObject({
         exitCode: 1,
-        stdout: expect.stringContaining(`Signature does not match`),
-        stderr: ``,
+        stderr: expect.stringContaining(`Signature does not match`),
+        stdout: `Installing pnpm@1.9998.9999 in the project...\n`,
       });
     });
   });
@@ -1757,8 +1947,8 @@ describe(`handle integrity checks`, () => {
       });
       await expect(runCli(cwd, [`use`, `yarn@1.9998.9999`], true)).resolves.toMatchObject({
         exitCode: 1,
-        stdout: expect.stringContaining(`Signature does not match`),
-        stderr: ``,
+        stderr: expect.stringContaining(`Signature does not match`),
+        stdout: `Installing yarn@1.9998.9999 in the project...\n`,
       });
     });
   });