diff --git a/commands/common/manifest.go b/commands/common/manifest.go
index d7db4aa..f511c50 100644
--- a/commands/common/manifest.go
+++ b/commands/common/manifest.go
@@ -85,11 +85,26 @@ func SaveManifest(mf *model.Manifest, dir ...string) error {
 	return err
 }
 
-// ReadSourceCode reads the content of the file pointed by SourceCodePath
+// ReadSourceCode reads the content of the file pointed by SourceCodePath.
+// The path must stay inside the current working directory (where manifest.json is read from), symlinks included.
 func ReadSourceCode(mf *model.Manifest) (string, error) {
 	log.Debug(fmt.Sprintf("Reading source code from %s", mf.SourceCodePath))
-	sourceBytes, err := os.ReadFile(mf.SourceCodePath)
+
+	if !filepath.IsLocal(mf.SourceCodePath) {
+		return "", invalidManifestErr(fmt.Sprintf("sourceCodePath '%s' must be a relative path inside the worker directory", mf.SourceCodePath))
+	}
+
+	root, err := os.OpenRoot(".")
+	if err != nil {
+		return "", err
+	}
+	defer func() { _ = root.Close() }()
+
+	sourceBytes, err := root.ReadFile(mf.SourceCodePath)
 	if err != nil {
+		if !os.IsNotExist(err) {
+			return "", invalidManifestErr(fmt.Sprintf("cannot read sourceCodePath '%s': %v", mf.SourceCodePath, err))
+		}
 		return "", err
 	}
 	return string(sourceBytes), nil
diff --git a/commands/common/manifest_test.go b/commands/common/manifest_test.go
index 22188e8..806b0e6 100644
--- a/commands/common/manifest_test.go
+++ b/commands/common/manifest_test.go
@@ -140,13 +140,28 @@ func TestReadManifestPreservesOmittedAndEmptyProperties(t *testing.T) {
 	}
 }
 
+func symlinkOrSkip(t *testing.T, target, link string) {
+	t.Helper()
+	if err := os.Symlink(target, link); err != nil {
+		t.Skipf("cannot create symlink: %v", err)
+	}
+}
+
+func rejected(t assert.TestingT, err error, _ ...interface{}) bool {
+	assert.ErrorContains(t, err, "must be a relative path inside the worker directory")
+	return false
+}
+
 func TestManifest_ReadSourceCode(t *testing.T) {
 	tests := []struct {
 		name       string
 		sourceCode string
 		manifest   *model.Manifest
-		want       string
-		wantErr    assert.ErrorAssertionFunc
+		// setup optionally prepares the folder and returns the manifest to use instead of manifest.
+		// outside is an existing file located outside dir.
+		setup   func(t *testing.T, dir, outside string) *model.Manifest
+		want    string
+		wantErr assert.ErrorAssertionFunc
 	}{
 		{
 			name:       "nominal case",
@@ -167,6 +182,76 @@ func TestManifest_ReadSourceCode(t *testing.T) {
 				return false
 			},
 		},
+		{
+			name: "nested relative path",
+			setup: func(t *testing.T, dir, _ string) *model.Manifest {
+				require.NoError(t, os.Mkdir(filepath.Join(dir, "sub"), 0o700))
+				require.NoError(t, os.WriteFile(filepath.Join(dir, "my-worker.ts"), []byte("nested"), 0o600))
+				return patchedManifestSample(func(mf *model.Manifest) { mf.SourceCodePath = "sub/../my-worker.ts" })
+			},
+			want:    "nested",
+			wantErr: assert.NoError,
+		},
+		{
+			name: "symlink inside the directory",
+			setup: func(t *testing.T, dir, _ string) *model.Manifest {
+				require.NoError(t, os.WriteFile(filepath.Join(dir, "my-worker.ts"), []byte("linked"), 0o600))
+				symlinkOrSkip(t, "my-worker.ts", filepath.Join(dir, "link.ts"))
+				return patchedManifestSample(func(mf *model.Manifest) { mf.SourceCodePath = "link.ts" })
+			},
+			want:    "linked",
+			wantErr: assert.NoError,
+		},
+		{
+			name: "absolute path outside the directory rejected",
+			setup: func(t *testing.T, _, outside string) *model.Manifest {
+				return patchedManifestSample(func(mf *model.Manifest) { mf.SourceCodePath = outside })
+			},
+			wantErr: rejected,
+		},
+		{
+			name: "absolute path inside the directory rejected",
+			setup: func(t *testing.T, dir, _ string) *model.Manifest {
+				require.NoError(t, os.WriteFile(filepath.Join(dir, "my-worker.ts"), []byte("x"), 0o600))
+				return patchedManifestSample(func(mf *model.Manifest) { mf.SourceCodePath = filepath.Join(dir, "my-worker.ts") })
+			},
+			wantErr: rejected,
+		},
+		{
+			name: "parent traversal rejected",
+			setup: func(t *testing.T, dir, outside string) *model.Manifest {
+				rel, err := filepath.Rel(dir, outside)
+				require.NoError(t, err)
+				return patchedManifestSample(func(mf *model.Manifest) { mf.SourceCodePath = rel })
+			},
+			wantErr: rejected,
+		},
+		{
+			name: "symlink escaping the directory rejected",
+			setup: func(t *testing.T, dir, outside string) *model.Manifest {
+				symlinkOrSkip(t, outside, filepath.Join(dir, "escape.ts"))
+				return patchedManifestSample(func(mf *model.Manifest) { mf.SourceCodePath = "escape.ts" })
+			},
+			wantErr: func(t assert.TestingT, err error, i ...interface{}) bool {
+				assert.ErrorContains(t, err, "invalid manifest:")
+				assert.ErrorContains(t, err, "cannot read sourceCodePath 'escape.ts'")
+				assert.ErrorContains(t, err, "path escapes")
+				assert.False(t, os.IsNotExist(err))
+				return false
+			},
+		},
+		{
+			name: "directory instead of a file",
+			setup: func(t *testing.T, dir, _ string) *model.Manifest {
+				require.NoError(t, os.Mkdir(filepath.Join(dir, "sub"), 0o700))
+				return patchedManifestSample(func(mf *model.Manifest) { mf.SourceCodePath = "sub" })
+			},
+			wantErr: func(t assert.TestingT, err error, i ...interface{}) bool {
+				assert.ErrorContains(t, err, "invalid manifest: cannot read sourceCodePath 'sub'")
+				assert.NotContains(t, err.Error(), "path escapes")
+				return false
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -183,10 +268,17 @@ func TestManifest_ReadSourceCode(t *testing.T) {
 				require.NoError(t, err)
 			}
 
-			err = os.Chdir(manifestFolder)
-			require.NoError(t, err)
+			manifest := tt.manifest
+			if tt.setup != nil {
+				outsideFolder := t.TempDir()
+				outside := filepath.Join(outsideFolder, "secret.txt")
+				require.NoError(t, os.WriteFile(outside, []byte("secret"), 0o600))
+				manifest = tt.setup(t, manifestFolder, outside)
+			}
+
+			t.Chdir(manifestFolder)
 
-			got, err := ReadSourceCode(manifestSample)
+			got, err := ReadSourceCode(manifest)
 			if !tt.wantErr(t, err, "ReadSourceCode()") {
 				return
 			}
diff --git a/commands/deploy_cmd_test.go b/commands/deploy_cmd_test.go
index 676ba3c..f9bc328 100644
--- a/commands/deploy_cmd_test.go
+++ b/commands/deploy_cmd_test.go
@@ -35,6 +35,18 @@ func TestDeployCommand(t *testing.T) {
 		wantErr        error
 		patchManifest  func(mf *model.Manifest)
 	}{
+		{
+			name:         "fails if source code path escapes the worker directory",
+			workerAction: "BEFORE_UPLOAD",
+			workerName:   "wk-escape",
+			serverBehavior: common.NewServerStub(t).
+				WithGetOneEndpoint().
+				WithOptionsEndpoint(),
+			patchManifest: func(mf *model.Manifest) {
+				mf.SourceCodePath = "../outside.ts"
+			},
+			wantErr: errors.New("invalid manifest: sourceCodePath '../outside.ts' must be a relative path inside the worker directory"),
+		},
 		{
 			name:         "create",
 			workerAction: "BEFORE_UPLOAD",
diff --git a/commands/dry_run_cmd_test.go b/commands/dry_run_cmd_test.go
index e1f260c..22457b9 100644
--- a/commands/dry_run_cmd_test.go
+++ b/commands/dry_run_cmd_test.go
@@ -35,6 +35,15 @@ func TestDryRun(t *testing.T) {
 		// If provided a temp file will be generated with this content and the file path will be added at the end of the command
 		fileInput string
 	}{
+		{
+			name:       "fails if source code path escapes the worker directory",
+			serverStub: common.NewServerStub(t),
+			patchManifest: func(mf *model.Manifest) {
+				mf.SourceCodePath = "../outside.ts"
+			},
+			commandArgs: []string{`{}`},
+			assert:      common.AssertOutputError("invalid manifest: sourceCodePath '../outside.ts' must be a relative path inside the worker directory"),
+		},
 		{
 			name: "nominal case",
 			serverStub: common.NewServerStub(t).