diff --git a/tools/packaging/linux-frame-copy-profile.cjs b/tools/packaging/linux-frame-copy-profile.cjs
index 6f00a0fab..85d505f82 100644
--- a/tools/packaging/linux-frame-copy-profile.cjs
+++ b/tools/packaging/linux-frame-copy-profile.cjs
@@ -51,13 +51,12 @@ function findLinuxFrameCopyProfile(value) {
     }
 
     const name = typeof value === 'string' ? value.trim() : String(value);
-    const profile = LINUX_FRAME_COPY_PROFILES[name];
-    if (!profile) {
+    if (!Object.hasOwn(LINUX_FRAME_COPY_PROFILES, name)) {
         throw new Error(
             `Unsupported Linux frame-copy profile "${name}". Expected one of: ${expectedProfileNames()}.`
         );
     }
-    return profile;
+    return LINUX_FRAME_COPY_PROFILES[name];
 }
 
 function resolveLinuxFrameCopyProfile(value) {
diff --git a/tools/packaging/linux-frame-copy-profile.test.mjs b/tools/packaging/linux-frame-copy-profile.test.mjs
index 17af18438..2cae643f5 100644
--- a/tools/packaging/linux-frame-copy-profile.test.mjs
+++ b/tools/packaging/linux-frame-copy-profile.test.mjs
@@ -109,6 +109,23 @@ test('rejects missing and unsupported profile names with clear errors', () => {
     );
 });
 
+test('rejects inherited object property names as unsupported profiles', () => {
+    for (const value of ['constructor', 'toString', '__proto__']) {
+        const unsupportedProfileError = new RegExp(
+            `Unsupported Linux frame-copy profile "${value}"`
+        );
+
+        assert.throws(
+            () => resolveLinuxFrameCopyProfile(value),
+            unsupportedProfileError
+        );
+        assert.throws(
+            () => validateLinuxProfileTargets(value, ['deb']),
+            unsupportedProfileError
+        );
+    }
+});
+
 test('validates profile targets case-insensitively with deterministic errors', () => {
     const targets = ['DEB', 'AppImage', 'RPM'];