{"id":"CVE-2026-10648","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-10648","generatedAt":"2026-10-28T02:20:20.544Z","title":"In default builds the __ASSERT_NO_MSG in net_buf_reset is a no-op, so net_buf_simple_reset writes through the NULL pointer (buf->len = 0; buf->data = buf->__buf), causing a fault/crash.","description":"mcumgr_serial_process_frag() in subsys/mgmt/mcumgr/transport/src/serial_util.c calls net_buf_reset() on the result of smp_packet_alloc() before checking it for NULL. smp_packet_alloc() uses net_buf_alloc(K_NO_WAIT) against the shared MCUmgr packet pool (CONFIG_MCUMGR_TRANSPORT_NETBUF_COUNT, default 4), which returns NULL when the pool is exhausted. In default builds the __ASSERT_NO_MSG in net_buf_reset is a no-op, so net_buf_simple_reset writes through the NULL pointer (buf->len = 0; buf->data = buf->__buf), causing a fault/crash.\n\nThe fragment data reaches this code from attacker-controlled bytes on the MCUmgr serial/UART/shell-console transports (smp_uart.c, smp_raw_uart.c, smp_shell.c), and a fresh buffer is allocated at the start of essentially every new packet. An attacker on the serial/console link can flood the transport to drive the 4-entry buffer pool to exhaustion and induce the NULL dereference, crashing the device (denial of service).\n\nThe defect was introduced after the original MCUmgr rework and shipped in Zephyr v4.4.0. The fix moves the NULL check ahead of net_buf_reset.","published":"2026-06-29T23:16:42.000Z","lastModified":"2026-10-25T21:10:01.000Z","status":"Modified","sourceIdentifier":"vulnerabilities@zephyrproject.org","cvss":{"version":"3.1","score":5.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-476"],"affected":["zephyrproject/zephyr"],"epss":{"score":0.00153,"percentile":0.04351,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.15%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/6f363ec6f7fd6ae9ed7ca2ae66fd9c82dce31c59","tags":["Patch"],"source":"vulnerabilities@zephyrproject.org"},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-j64f-h3ww-f32c","tags":["Exploit","Patch","Vendor Advisory"],"source":"vulnerabilities@zephyrproject.org"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-10648","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}