{"cve":"CVE-2026-43418","nvd":{"published":"2026-05-08T15:16:53.803","modified":"2026-06-17T10:49:33.627","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/mmcid: Prevent CID stalls due to concurrent forks\n\nA newly forked task is accounted as MMCID user before the task is visible\nin the process' thread list and the global task list. This creates the\nfollowing problem:\n\n CPU1\t\t\tCPU2\n fork()\n   sched_mm_cid_fork(tnew1)\n     tnew1->mm.mm_cid_users++;\n     tnew1->mm_cid.cid = getcid()\n-> preemption\n\t\t\tfork()\n\t\t\t  sched_mm_cid_fork(tnew2)\n\t\t\t    tnew2->mm.mm_cid_users++;\n                            // Reaches the per CPU threshold\n\t\t\t    mm_cid_fixup_tasks_to_cpus()\n\t\t\t    for_each_other(current, p)\n\t\t\t         ....\n\nAs tnew1 is not visible yet, this fails to fix up the already allocated CID\nof tnew1. As a consequence a subsequent schedule in might fail to acquire a\n(transitional) CID and the machine stalls.\n\nMove the invocation of sched_mm_cid_fork() after the new task becomes\nvisible in the thread and the task list to prevent this.\n\nThis also makes it symmetrical vs. exit() where the task is removed as CID\nuser before the task is removed from the thread and task lists.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/b2e48c429ec54715d16fefa719dd2fbded2e65be","https://git.kernel.org/stable/c/f0189d49282e0458f3a737bd486c1ec048148f66"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:33:55.586217763+00:00"},"epss":{"cve":"CVE-2026-43418","score":0.00107,"percentile":0.01149,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}