diff --git a/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtComputingResource.java b/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtComputingResource.java
index 7c3f826be171..4c3fc56b6843 100644
--- a/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtComputingResource.java
+++ b/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtComputingResource.java
@@ -332,7 +332,7 @@ public class LibvirtComputingResource extends ServerResourceBase implements Serv
     private static final String KVMCLOCK = "kvmclock";
     private static final String HYPERVCLOCK = "hypervclock";
     private static final String WINDOWS = "Windows";
-    private static final String X86_DEFAULT_VIDEO_MODEL = "vga";
+    private static final VideoDef.VideoModel X86_DEFAULT_VIDEO_MODEL = VideoDef.VideoModel.VGA;
     private static final int X86_DEFAULT_VIDEO_RAM_KIB = 32768;
     private static final String Q35 = "q35";
     private static final String PTY = "pty";
@@ -3352,26 +3352,35 @@ protected ConsoleDef createConsoleDef() {
 
     protected VideoDef createVideoDef(VirtualMachineTO vmTO) {
         Map<String, String> details = vmTO.getDetails();
-        String videoHw = this.videoHw;
+        VideoDef.VideoModel videoModel = VideoDef.VideoModel.fromString(this.videoHw);
+        if (videoModel == null && StringUtils.isNotBlank(this.videoHw)) {
+            LOGGER.warn("Ignoring unsupported video model '{}' from {}", this.videoHw, AgentProperties.VM_VIDEO_HARDWARE.getName());
+        }
         int videoRam = this.videoRam;
         if (details != null) {
             if (details.containsKey(VmDetailConstants.VIDEO_HARDWARE)) {
-                videoHw = details.get(VmDetailConstants.VIDEO_HARDWARE);
+                String requested = details.get(VmDetailConstants.VIDEO_HARDWARE);
+                VideoDef.VideoModel requestedModel = VideoDef.VideoModel.fromString(requested);
+                if (requestedModel != null) {
+                    videoModel = requestedModel;
+                } else {
+                    LOGGER.warn("Ignoring unsupported {} '{}' of VM {}", VmDetailConstants.VIDEO_HARDWARE, requested, vmTO.getName());
+                }
             }
             if (details.containsKey(VmDetailConstants.VIDEO_RAM)) {
                 String value = details.get(VmDetailConstants.VIDEO_RAM);
                 videoRam = NumbersUtil.parseInt(value, videoRam);
             }
         }
-        if (StringUtils.isBlank(videoHw) && isGuestX86(vmTO)) {
+        if (videoModel == null && isGuestX86(vmTO)) {
             // With no <video> element libvirt defaults x86 guests to cirrus, which is deprecated
             // in QEMU and renders a blank console on recent Windows guests (e.g. Windows Server 2025 Core)
-            videoHw = X86_DEFAULT_VIDEO_MODEL;
+            videoModel = X86_DEFAULT_VIDEO_MODEL;
             if (videoRam == 0) {
                 videoRam = X86_DEFAULT_VIDEO_RAM_KIB;
             }
         }
-        return new VideoDef(videoHw, videoRam);
+        return new VideoDef(videoModel, videoRam);
     }
 
     protected RngDef createRngDef() {
@@ -3472,7 +3481,15 @@ private CpuModeDef createCpuModeDef(VirtualMachineTO vmTO, int vcpus) {
         final CpuModeDef cmd = new CpuModeDef();
         Map<String, String> details = vmTO.getDetails();
         String cpuMode = MapUtils.isNotEmpty(details) && details.get(VmDetailConstants.GUEST_CPU_MODE) != null ? details.get(VmDetailConstants.GUEST_CPU_MODE) : guestCpuMode;
-        String cpuModel = MapUtils.isNotEmpty(details) && details.get(VmDetailConstants.GUEST_CPU_MODEL) != null ? details.get(VmDetailConstants.GUEST_CPU_MODEL) : guestCpuModel;
+        String cpuModel = guestCpuModel;
+        if (MapUtils.isNotEmpty(details) && details.get(VmDetailConstants.GUEST_CPU_MODEL) != null) {
+            String requested = details.get(VmDetailConstants.GUEST_CPU_MODEL);
+            if (CpuModeDef.isValidModelName(requested)) {
+                cpuModel = requested;
+            } else {
+                LOGGER.warn("Ignoring invalid {} '{}' of VM {}", VmDetailConstants.GUEST_CPU_MODEL, requested, vmTO.getName());
+            }
+        }
         cmd.setMode(cpuMode);
         cmd.setModel(cpuModel);
         cmd.setFeatures(cpuFeatures);
diff --git a/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtVMDef.java b/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtVMDef.java
index 439e4f663416..353b068faebb 100644
--- a/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtVMDef.java
+++ b/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtVMDef.java
@@ -26,6 +26,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.regex.Pattern;
 
 import com.cloud.cpu.CPU;
 import org.apache.cloudstack.api.ApiConstants.IoDriverPolicy;
@@ -1994,6 +1995,12 @@ public String toString() {
     }
 
     public static class CpuModeDef {
+        /**
+         * CPU model names as QEMU and libvirt define them, such as Nehalem, EPYC-Rome-v2 or x86-64-v2.
+         * The model reaches the domain XML from a VM detail, so anything else is rejected.
+         */
+        private static final Pattern CPU_MODEL_NAME = Pattern.compile("^[A-Za-z0-9][A-Za-z0-9._+-]*$");
+
         private String _mode;
         private String _model;
         private List<String> _features;
@@ -2001,6 +2008,10 @@ public static class CpuModeDef {
         private int _threadsPerCore = -1;
         private int _sockets = -1;
 
+        public static boolean isValidModelName(String model) {
+            return model != null && CPU_MODEL_NAME.matcher(model).matches();
+        }
+
         public void setMode(String mode) {
             _mode = mode;
         }
@@ -2011,7 +2022,14 @@ public void setFeatures(List<String> features) {
             }
         }
 
+        /**
+         * Sets the CPU model for the custom mode. A name that is not a plain QEMU model name is ignored.
+         */
         public void setModel(String model) {
+            if (model != null && !isValidModelName(model)) {
+                LOGGER.warn("Ignoring CPU model '{}' because it is not a valid model name", model);
+                return;
+            }
             _model = model;
         }
 
@@ -2090,18 +2108,57 @@ public String toString() {
     }
 
     public static class VideoDef {
-        private String _videoModel;
+        /**
+         * Video model types accepted by libvirt. The model name reaches the domain XML
+         * from a VM detail, so only values from this list are ever emitted.
+         */
+        public enum VideoModel {
+            VGA("vga"), CIRRUS("cirrus"), VMVGA("vmvga"), XEN("xen"), VBOX("vbox"), QXL("qxl"), VIRTIO("virtio"), GOP("gop"), BOCHS("bochs"), RAMFB("ramfb"), NONE("none");
+
+            private final String model;
+
+            VideoModel(String model) {
+                this.model = model;
+            }
+
+            @Override
+            public String toString() {
+                return model;
+            }
+
+            /**
+             * Returns the matching model, ignoring case, or null when the value is blank or unknown.
+             */
+            public static VideoModel fromString(String model) {
+                if (StringUtils.isBlank(model)) {
+                    return null;
+                }
+                String trimmed = model.trim();
+                for (VideoModel videoModel : values()) {
+                    if (videoModel.model.equalsIgnoreCase(trimmed)) {
+                        return videoModel;
+                    }
+                }
+                return null;
+            }
+        }
+
+        private VideoModel _videoModel;
         private int _videoRam;
 
-        public VideoDef(String videoModel, int videoRam) {
+        public VideoDef(VideoModel videoModel, int videoRam) {
             _videoModel = videoModel;
             _videoRam = videoRam;
         }
 
+        public VideoModel getVideoModel() {
+            return _videoModel;
+        }
+
         @Override
         public String toString() {
             StringBuilder videoBuilder = new StringBuilder();
-            if (_videoModel != null && !_videoModel.isEmpty()){
+            if (_videoModel != null) {
                 videoBuilder.append("<video>\n");
                 if (_videoRam != 0) {
                     videoBuilder.append("<model type='" + _videoModel + "' vram='" + _videoRam + "'/>\n");
diff --git a/plugins/hypervisors/kvm/src/test/java/com/cloud/hypervisor/kvm/resource/LibvirtComputingResourceTest.java b/plugins/hypervisors/kvm/src/test/java/com/cloud/hypervisor/kvm/resource/LibvirtComputingResourceTest.java
index 33fb377bc90e..ff57dfdb1b06 100644
--- a/plugins/hypervisors/kvm/src/test/java/com/cloud/hypervisor/kvm/resource/LibvirtComputingResourceTest.java
+++ b/plugins/hypervisors/kvm/src/test/java/com/cloud/hypervisor/kvm/resource/LibvirtComputingResourceTest.java
@@ -705,14 +705,53 @@ public void testCreateConsoleDef() {
     public void testCreateVideoDef() {
         VirtualMachineTO to = createDefaultVM(false);
         libvirtComputingResourceSpy.videoRam = 200;
-        libvirtComputingResourceSpy.videoHw = "vGPU";
+        libvirtComputingResourceSpy.videoHw = "VmVGA";
 
         VideoDef videoDef = libvirtComputingResourceSpy.createVideoDef(to);
         Document domainDoc = parse(videoDef.toString());
-        assertXpath(domainDoc, "/video/model/@type", "vGPU");
+        assertXpath(domainDoc, "/video/model/@type", "vmvga");
         assertXpath(domainDoc, "/video/model/@vram", "200");
     }
 
+    @Test
+    public void testCreateVideoDefIgnoresUnsupportedAgentProperty() {
+        VirtualMachineTO to = createDefaultVM(false);
+        libvirtComputingResourceSpy.videoHw = "vGPU";
+
+        VideoDef videoDef = libvirtComputingResourceSpy.createVideoDef(to);
+        Document domainDoc = parse(videoDef.toString());
+        assertXpath(domainDoc, "/video/model/@type", "vga");
+        assertXpath(domainDoc, "/video/model/@vram", "32768");
+    }
+
+    @Test
+    public void testCreateVideoDefIgnoresInjectedDetail() {
+        VirtualMachineTO to = createDefaultVM(false);
+        Map<String, String> details = new HashMap<>();
+        details.put(VmDetailConstants.VIDEO_HARDWARE, "virtio'/></video><disk type='file' device='disk'><driver name='qemu' type='raw'/>"
+                + "<source file='/etc/shadow'/><target dev='vdz' bus='virtio'/></disk><video><model type='virtio");
+        to.setDetails(details);
+
+        VideoDef videoDef = libvirtComputingResourceSpy.createVideoDef(to);
+        String xml = videoDef.toString();
+        assertFalse(xml.contains("<disk"));
+        Document domainDoc = parse(xml);
+        assertXpath(domainDoc, "/video/model/@type", "vga");
+    }
+
+    @Test
+    public void testCreateVideoDefUnknownDetailKeepsAgentProperty() {
+        VirtualMachineTO to = createDefaultVM(false);
+        libvirtComputingResourceSpy.videoHw = "qxl";
+        Map<String, String> details = new HashMap<>();
+        details.put(VmDetailConstants.VIDEO_HARDWARE, "bogus");
+        to.setDetails(details);
+
+        VideoDef videoDef = libvirtComputingResourceSpy.createVideoDef(to);
+        Document domainDoc = parse(videoDef.toString());
+        assertXpath(domainDoc, "/video/model/@type", "qxl");
+    }
+
     @Test
     public void testCreateVideoDefX86DefaultsToVga() {
         VirtualMachineTO to = createDefaultVM(false);
diff --git a/plugins/hypervisors/kvm/src/test/java/com/cloud/hypervisor/kvm/resource/LibvirtVMDefTest.java b/plugins/hypervisors/kvm/src/test/java/com/cloud/hypervisor/kvm/resource/LibvirtVMDefTest.java
index 56ad267eac7e..a6c3301e01f0 100644
--- a/plugins/hypervisors/kvm/src/test/java/com/cloud/hypervisor/kvm/resource/LibvirtVMDefTest.java
+++ b/plugins/hypervisors/kvm/src/test/java/com/cloud/hypervisor/kvm/resource/LibvirtVMDefTest.java
@@ -213,6 +213,37 @@ public void testCpuModeDef() {
 
     }
 
+    @Test
+    public void testCpuModeDefIgnoresInvalidModelName() {
+        LibvirtVMDef.CpuModeDef cpuModeDef = new LibvirtVMDef.CpuModeDef();
+        cpuModeDef.setMode("custom");
+        cpuModeDef.setModel("Nehalem</model></cpu><devices><disk type='file'/></devices><cpu><model>x");
+
+        assertEquals("<cpu></cpu>", cpuModeDef.toString());
+        assertTrue(LibvirtVMDef.CpuModeDef.isValidModelName("EPYC-Rome-v2"));
+        assertTrue(LibvirtVMDef.CpuModeDef.isValidModelName("x86-64-v2"));
+        assertTrue(LibvirtVMDef.CpuModeDef.isValidModelName("Skylake-Client-noTSX-IBRS"));
+        assertFalse(LibvirtVMDef.CpuModeDef.isValidModelName(""));
+        assertFalse(LibvirtVMDef.CpuModeDef.isValidModelName("-Nehalem"));
+        assertFalse(LibvirtVMDef.CpuModeDef.isValidModelName("Nehalem Broadwell"));
+        assertFalse(LibvirtVMDef.CpuModeDef.isValidModelName("Nehalem<"));
+    }
+
+    @Test
+    public void testVideoDefOnlyEmitsKnownModels() {
+        assertEquals(LibvirtVMDef.VideoDef.VideoModel.VIRTIO, LibvirtVMDef.VideoDef.VideoModel.fromString("VirtIO"));
+        assertEquals(LibvirtVMDef.VideoDef.VideoModel.QXL, LibvirtVMDef.VideoDef.VideoModel.fromString(" qxl "));
+        assertNull(LibvirtVMDef.VideoDef.VideoModel.fromString(null));
+        assertNull(LibvirtVMDef.VideoDef.VideoModel.fromString(""));
+        assertNull(LibvirtVMDef.VideoDef.VideoModel.fromString("virtio'/></video><disk type='file'/><video><model type='virtio"));
+
+        assertEquals("", new LibvirtVMDef.VideoDef(null, 65536).toString());
+        assertEquals("<video>\n<model type='virtio' vram='65536'/>\n</video>\n",
+                new LibvirtVMDef.VideoDef(LibvirtVMDef.VideoDef.VideoModel.VIRTIO, 65536).toString());
+        assertEquals("<video>\n<model type='vga'/>\n</video>\n",
+                new LibvirtVMDef.VideoDef(LibvirtVMDef.VideoDef.VideoModel.VGA, 0).toString());
+    }
+
     @Test
     public void testCpuModeDefCpuFeatures() {
         LibvirtVMDef.CpuModeDef cpuModeDef = new LibvirtVMDef.CpuModeDef();