{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-12631",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-19T13:17:32.022813Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-19T13:18:03.745Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://github.com/zephyrproject-rtos/zephyr",
          "defaultStatus": "unaffected",
          "packageName": "zephyr",
          "product": "zephyr",
          "programFiles": [
            "kernel/thread.c"
          ],
          "vendor": "zephyrproject",
          "versions": [
            {
              "lessThan": "4.4.2",
              "status": "affected",
              "version": "2.3.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "The Zephyr kernel validates the k_thread_join() and k_thread_abort() system calls (declared __syscall in include/zephyr/kernel.h) through thread_obj_validate() in kernel/thread.c. Its default switch branch is the access-denied path, taken when k_object_validate() returns -EPERM (the calling user thread was never granted access to the target thread object) or -EBADF (the supplied pointer is not a registered kernel object of the right type). That branch invoked K_OOPS(K_SYSCALL_VERIFY_MSG(ret, \"access denied\")), but K_SYSCALL_VERIFY_MSG treats a true expression as success; the non-zero error code ret therefore read as \"verified OK\", the kernel oops was never raised, and control fell through to CODE_UNREACHABLE.\n\nBecause k_thread_join() and k_thread_abort() are system calls, an unprivileged user-mode thread (under CONFIG_USERSPACE) can reach this denial path directly by calling either syscall on a thread object it does not own. Instead of the offending thread being cleanly terminated, execution reaches __builtin_unreachable() while running in supervisor mode inside the syscall handler.\n\nOn Clang builds CODE_UNREACHABLE emits an illegal-instruction trap, so a user thread can deterministically crash the kernel \u2014 a locally triggerable denial of service that escapes the userspace sandbox. On GCC builds the path is undefined behavior: the compiler may drop the return-value handling for thread_obj_validate(), so it can return an undefined bool; if that is false, the caller proceeds into the real k_thread_join()/k_thread_abort() implementation for a thread the user was never authorized to access, an access-control bypass.\n\nThe fix changes the verification expression to ret == 0, so a denied (non-zero) result now correctly raises K_OOPS and terminates the offending caller."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 6.5,
            "baseSeverity": "MEDIUM",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H",
            "version": "3.1"
          },
          "format": "CVSS"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-862",
              "description": "auth",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-18T20:55:42.859Z",
        "orgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
        "shortName": "zephyr"
      },
      "references": [
        {
          "name": "Fix commit",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/zephyrproject-rtos/zephyr/commit/bd1828652dfc217ba9f3a2221a7499cd8914ed9c"
        },
        {
          "name": "GHSA-crfw-75jw-hjm3",
          "url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-crfw-75jw-hjm3"
        }
      ],
      "title": "Broken access-control denial in k_thread_join/k_thread_abort syscall validation in Zephyr kernel",
      "x_generator": {
        "engine": "cvelib 1.8.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
    "assignerShortName": "zephyr",
    "cveId": "CVE-2026-12631",
    "datePublished": "2026-08-18T20:55:42.859Z",
    "dateReserved": "2026-06-18T15:22:26.927Z",
    "dateUpdated": "2026-08-19T13:18:03.745Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}