CVE-2026-31734

/* * PoC for CVE-2026-31734 * This is a conceptual demonstration of the logic flaw. * Triggering the actual bug requires a specific sched_ext configuration * and a non-PREEMPT_RCU kernel environment. */ #include <linux/bpf.h> #include <bpf/bpf_helpers.h> SEC("sk_buff/verdict") int trigger_migration_bug(struct __sk_buff *skb) { // In a non-PREEMPT_RCU kernel, this logic path // might lead to the false negative described in the CVE. // The actual exploit involves complex interactions with sched_ext ops. return 0; } char _license[] SEC("license") = "GPL";

{"cve": {"id": "CVE-2026-31734", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T15:16:36.030", "lastModified": "2026-05-07T16:50:47.197", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Fix is_bpf_migration_disabled() false negative on non-PREEMPT_RCU\n\nSince commit 8e4f0b1ebcf2 (\"bpf: use rcu_read_lock_dont_migrate() for\ntrampoline.c\"), the BPF prolog (__bpf_prog_enter) calls migrate_disable()\nonly when CONFIG_PREEMPT_RCU is enabled, via rcu_read_lock_dont_migrate().\nWithout CONFIG_PREEMPT_RCU, the prolog never touches migration_disabled,\nso migration_disabled == 1 always means the task is truly\nmigration-disabled regardless of whether it is the current task.\n\nThe old unconditional p == current check was a false negative in this\ncase, potentially allowing a migration-disabled task to be dispatched to\na remote CPU and triggering scx_error in task_can_run_on_remote_rq().\n\nOnly apply the p == current disambiguation when CONFIG_PREEMPT_RCU is\nenabled, where the ambiguity with the BPF prolog still exists."}], "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": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18", "versionEndExcluding": "6.18.22", "matchCriteriaId": "BFDF75B5-A823-4448-88D3-3029C0464168"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.12", "matchCriteriaId": "0A2B9540-02D5-41B4-B16A-82AF66FD4F36"}, {"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"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/0c4a59df370bea245695c00aaae6ae75747139bd", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/72c43eb2e334febe93018cfb68ae828f55c6e49e", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/b4992a9446bb9a639007bfd32bf5c5a7e30199e5", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}