{"resultsPerPage":1,"startIndex":0,"totalResults":1,"format":"NVD_CVE","version":"2.0","timestamp":"2026-07-26T18:55:25.987","vulnerabilities":[{"cve":{"id":"CVE-2026-10681","sourceIdentifier":"vulnerabilities@zephyrproject.org","published":"2026-07-25T14:16:28.957","lastModified":"2026-07-25T14:16:28.957","vulnStatus":"Received","cveTags":[],"descriptions":[{"lang":"en","value":"In Zephyr's userspace dynamic-objects subsystem, thread_idx_alloc() in kernel/userspace/userspace.c allocated a new thread permission index from the global _thread_idx_map[] bitmap without holding lists_lock.\n\nOn SMP systems, two user-mode threads invoking the k_object_alloc(K_OBJ_THREAD) syscall concurrently can both observe the same low free bit, perform the same non-atomic RMW to clear it, and return the identical tidx.\n\nThe two newly created K_OBJ_THREAD objects are then assigned the same thread_id, so the two user threads alias a single bit position in every kernel object's perms[] bitfield: any subsequent grant of access on a kernel object to one thread is implicitly a grant to the other, defeating userspace ACL isolation. A secondary lost-update window between the unlocked &=~BIT() in alloc and the locked |= BIT() in thread_idx_free() can also leak entries from the thread-index pool.\n\nThe defect is reachable from any user-mode thread via the unrestricted __syscall k_object_alloc and is gated on CONFIG_USERSPACE, CONFIG_DYNAMIC_OBJECTS, and CONFIG_SMP. The flaw was introduced when the per-thread permission index was added in 2018 and is present in every release up to and including v4.4.0. Fixed by holding lists_lock across the bitmap RMW and the permissions clear (and inlining the obj_list traversal that previously took the lock itself)."}],"affected":[{"source":"vulnerabilities@zephyrproject.org","affectedData":[{"vendor":"zephyrproject","product":"zephyr","defaultStatus":"unaffected","collectionURL":"https://github.com/zephyrproject-rtos/zephyr","packageName":"zephyr","programFiles":["kernel/userspace/userspace.c"],"versions":[{"version":"2.0.0","lessThan":"4.5.0","versionType":"semver","status":"affected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"vulnerabilities@zephyrproject.org","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L","baseScore":6.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"LOW"},"exploitabilityScore":1.0,"impactScore":5.5}]},"weaknesses":[{"source":"vulnerabilities@zephyrproject.org","type":"Secondary","description":[{"lang":"en","value":"CWE-362"}]}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/862ea2fbbeb2ccdf8ff994b03e2e3b4405f2c37d","source":"vulnerabilities@zephyrproject.org"},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-j693-5rh5-8g8h","source":"vulnerabilities@zephyrproject.org"}]}}]}