{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-12366",
        "assignerOrgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
        "state": "PUBLISHED",
        "assignerShortName": "zephyr",
        "dateReserved": "2026-06-16T03:53:46.485Z",
        "datePublished": "2026-08-14T17:52:07.021Z",
        "dateUpdated": "2026-08-14T19:21:33.514Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
                "shortName": "zephyr",
                "dateUpdated": "2026-08-14T17:52:07.021Z"
            },
            "title": "Use-after-free freeing an armed dynamically-allocated k_timer in Zephyr userspace object disposal",
            "descriptions": [
                {
                    "lang": "en",
                    "value": "Zephyr's dynamic kernel-object disposal path unref_check() in kernel/userspace/userspace.c frees an object's storage (k_free(dyn->data)) once its reference count reaches zero, after running a per-object-type cleanup. The cleanup switch handled only K_OBJ_MSGQ and K_OBJ_STACK; there was no K_OBJ_TIMER case. A dynamically-allocated, initialized, and armed k_timer keeps its embedded struct _timeout dnode linked in the global timeout queue (_timeout_q), so freeing the timer storage without cancelling the timeout leaves a dangling node in that queue.\n\nWhen the timer next expires, the timeout machinery walks _timeout_q and invokes z_timer_expiration_handler() on the freed node, dereferencing and writing freed (and reusable) kernel heap in kernel/ISR context. This is a deterministic use-after-free that does not depend on SMP: the queued node is simply never unlinked at free time.\n\nThe disposal is reachable from an unprivileged user thread under CONFIG_USERSPACE + CONFIG_DYNAMIC_OBJECTS: a thread that holds the last permission on such a timer drops it via the k_object_release() syscall (or by exiting, through k_thread_perms_all_clear()), and can arm the timer itself via the k_timer_start() syscall. The free and the expiration handler run at kernel privilege while the actor is a user thread, so the bug is a sandbox-escape memory-corruption primitive usable for privilege escalation. The fix adds k_timer_cleanup() (cancel the timeout and wait for any in-flight handler) and calls it for K_OBJ_TIMER before freeing."
                }
            ],
            "affected": [
                {
                    "vendor": "zephyrproject",
                    "product": "zephyr",
                    "collectionURL": "https://github.com/zephyrproject-rtos/zephyr",
                    "packageName": "zephyr",
                    "defaultStatus": "unaffected",
                    "programFiles": [
                        "include/zephyr/kernel.h",
                        "include/zephyr/tracing/tracing.h",
                        "kernel/timer.c",
                        "kernel/userspace/userspace.c",
                        "subsys/tracing/ctf/tracing_ctf.h",
                        "subsys/tracing/sysview/tracing_sysview.h",
                        "subsys/tracing/test/tracing_test.h",
                        "subsys/tracing/user/tracing_user.h"
                    ],
                    "versions": [
                        {
                            "version": "1.12.0",
                            "status": "affected",
                            "lessThan": "4.5.0",
                            "versionType": "semver"
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://github.com/zephyrproject-rtos/zephyr/commit/1e68351a2572f9ae480be71da4aca9aa90db3fb2",
                    "name": "Fix commit",
                    "tags": [
                        "patch"
                    ]
                },
                {
                    "url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-x96g-542c-gccq",
                    "name": "GHSA-x96g-542c-gccq"
                }
            ],
            "metrics": [
                {
                    "format": "CVSS",
                    "cvssV3_1": {
                        "version": "3.1",
                        "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
                        "baseScore": 8.8,
                        "baseSeverity": "HIGH"
                    }
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "description": "use-after-free",
                            "cweId": "CWE-416",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "x_generator": {
                "engine": "cvelib 1.8.0"
            }
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-08-14T19:21:20.823611Z",
                                "id": "CVE-2026-12366",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "no"
                                    },
                                    {
                                        "Technical Impact": "total"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-08-14T19:21:33.514Z"
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}