diff --git a/src/libANGLE/renderer/gl/egl/DisplayEGL.cpp b/src/libANGLE/renderer/gl/egl/DisplayEGL.cpp
index 8ebc52f5ac..10ec3dffee 100644
--- a/src/libANGLE/renderer/gl/egl/DisplayEGL.cpp
+++ b/src/libANGLE/renderer/gl/egl/DisplayEGL.cpp
@@ -197,6 +197,12 @@ egl::Error DisplayEGL::initializeContext(EGLContext shareContext,
         {
             egl::AttributeMap attribsWithRobustness(attribs);
 
+            // Request robust buffer access on the native context. Without this
+            // bit, GL_KHR_robust_buffer_access_behavior advertised by the
+            // driver does not apply, and ANGLE incorrectly disables its own
+            // CPU-side OOB validation while the driver is free to fetch OOB.
+            // Matches GLX_CONTEXT_ROBUST_ACCESS_BIT_ARB / WGL equivalent.
+            attribsWithRobustness.insert(EGL_CONTEXT_OPENGL_ROBUST_ACCESS_EXT, EGL_TRUE);
             attribsWithRobustness.insert(EGL_CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY,
                                          EGL_LOSE_CONTEXT_ON_RESET);
             if (mHasNVRobustnessVideoMemoryPurge)
diff --git a/src/libANGLE/renderer/gl/renderergl_utils.cpp b/src/libANGLE/renderer/gl/renderergl_utils.cpp
index b8219a1080..26b79a2daa 100644
--- a/src/libANGLE/renderer/gl/renderergl_utils.cpp
+++ b/src/libANGLE/renderer/gl/renderergl_utils.cpp
@@ -1712,8 +1712,16 @@ void GenerateCaps(const FunctionsGL *functions,
                                 functions->isAtLeastGLES(gl::Version(3, 2)) ||
                                 functions->hasGLESExtension("GL_KHR_robustness");
 
+    // GL_KHR_robust_buffer_access_behavior only guarantees defined OOB
+    // behaviour when the context was created with the robust-access flag.
+    // The extension string alone is insufficient — verify the flag is set so
+    // we don't disable ANGLE's CPU-side bounds validation against a context
+    // that the driver is permitted to fetch OOB on.
+    GLint nativeContextFlags = 0;
+    functions->getIntegerv(GL_CONTEXT_FLAGS, &nativeContextFlags);
     extensions->robustBufferAccessBehaviorKHR =
         extensions->robustnessEXT &&
+        (nativeContextFlags & GL_CONTEXT_FLAG_ROBUST_ACCESS_BIT) != 0 &&
         (functions->hasGLExtension("GL_ARB_robust_buffer_access_behavior") ||
          functions->hasGLESExtension("GL_KHR_robust_buffer_access_behavior"));