diff --git a/packages/glob/__tests__/hash-files.test.ts b/packages/glob/__tests__/hash-files.test.ts
index 1ab4c524cf..d5d3d687c0 100644
--- a/packages/glob/__tests__/hash-files.test.ts
+++ b/packages/glob/__tests__/hash-files.test.ts
@@ -269,6 +269,46 @@ describe('globber', () => {
     }
   })
 
+  it('honors an explicit root outside the workspace without the opt-in', async () => {
+    // Mirrors the documented GITHUB_ACTION_PATH usage: an action passes its own
+    // directory as an allowed root, and that directory is not under the workspace.
+    const insideRoot = path.join(getTestTemp(), 'explicit-root-inside')
+    await fs.mkdir(insideRoot, {recursive: true})
+    await fs.writeFile(path.join(insideRoot, 'inside.txt'), 'inside content')
+
+    // Outside GITHUB_WORKSPACE (which the suite pins to __dirname).
+    const actionRoot = await fs.mkdtemp(
+      path.join(os.tmpdir(), 'hash-files-explicit-root-')
+    )
+    try {
+      await fs.writeFile(path.join(actionRoot, 'action.txt'), 'action content')
+
+      const patterns = `${insideRoot}/*\n${actionRoot}/*`
+
+      const insideOnly = await hashFiles(`${insideRoot}/*`, '', {
+        roots: [insideRoot]
+      })
+      expect(insideOnly).not.toEqual('')
+
+      // The explicit roots list is the allowlist, so files under actionRoot
+      // must be hashed even though allowFilesOutsideWorkspace is not set.
+      const both = await hashFiles(patterns, '', {
+        roots: [insideRoot, actionRoot]
+      })
+      expect(both).not.toEqual('')
+      expect(both).not.toEqual(insideOnly)
+
+      // And it hashes exactly those two files, no more.
+      const expected = await hashFiles(patterns, '', {
+        roots: [insideRoot, actionRoot],
+        allowFilesOutsideWorkspace: true
+      })
+      expect(both).toEqual(expected)
+    } finally {
+      await io.rmRF(actionRoot)
+    }
+  })
+
   it('applies relative exclude patterns across all allowed roots', async () => {
     const root = path.join(getTestTemp(), 'exclude-across-roots')
     const dir1 = path.join(root, 'dir1')
diff --git a/packages/glob/src/internal-hash-files.ts b/packages/glob/src/internal-hash-files.ts
index 3ffaf811cd..888bc49486 100644
--- a/packages/glob/src/internal-hash-files.ts
+++ b/packages/glob/src/internal-hash-files.ts
@@ -113,7 +113,12 @@ export async function hashFiles(
   const excludeMatchers = buildExcludeMatchers(options?.exclude ?? [])
 
   // Resolve roots up front; warn and skip any that fail to resolve.
-  // If allowFilesOutsideWorkspace is not enabled, roots are restricted to the resolved workspace.
+  // When the caller did not specify roots, the workspace is the only allowed
+  // root and `allowFilesOutsideWorkspace` is the opt-in that widens it.
+  // An explicit `roots` list is itself the allowlist, so its entries are
+  // honored as given - otherwise a root outside the workspace would be
+  // dropped here and the files under it silently skipped.
+  const explicitRoots = options?.roots !== undefined
   const resolvedRootsSet = new Set<string>()
   const roots = options?.roots ?? [resolvedWorkspace]
 
@@ -123,6 +128,7 @@ export async function hashFiles(
         root === resolvedWorkspace ? root : fs.realpathSync(root)
 
       if (
+        !explicitRoots &&
         !allowOutside &&
         !isInResolvedRoots(resolvedRoot, [resolvedWorkspace])
       ) {