CVE-2026-43418— sched/mmcid: Prevent CID stalls due to concurrent forks
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I. Basic Information for CVE-2026-43418
Vulnerability Information
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Vulnerability Title
sched/mmcid: Prevent CID stalls due to concurrent forks
Source: NVD (National Vulnerability Database)
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: sched/mmcid: Prevent CID stalls due to concurrent forks A newly forked task is accounted as MMCID user before the task is visible in the process' thread list and the global task list. This creates the following problem: CPU1 CPU2 fork() sched_mm_cid_fork(tnew1) tnew1->mm.mm_cid_users++; tnew1->mm_cid.cid = getcid() -> preemption fork() sched_mm_cid_fork(tnew2) tnew2->mm.mm_cid_users++; // Reaches the per CPU threshold mm_cid_fixup_tasks_to_cpus() for_each_other(current, p) .... As tnew1 is not visible yet, this fails to fix up the already allocated CID of tnew1. As a consequence a subsequent schedule in might fail to acquire a (transitional) CID and the machine stalls. Move the invocation of sched_mm_cid_fork() after the new task becomes visible in the thread and the task list to prevent this. This also makes it symmetrical vs. exit() where the task is removed as CID user before the task is removed from the thread and task lists.
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于sched/mmcid模块在fork()过程中新任务尚未可见时即分配CID，导致并发fork引发CID分配失败。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-43418
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Same Patch Batch · Linux · 2026-05-08 · 199 CVEs total
| CVE-2026-43376 | 9.8 CRITICAL | ksmbd: fix use-after-free by using call_rcu() for oplock_info |
| CVE-2026-43414 | 9.8 CRITICAL | scsi: qla2xxx: Completely fix fcport double free |
| CVE-2026-43341 | 9.8 CRITICAL | net/ipv6: ioam6: prevent schema length wraparound in trace fill |
| CVE-2026-43304 | 9.8 CRITICAL | libceph: define and enforce CEPH_MAX_KEY_LEN |
| CVE-2026-43402 | 9.8 CRITICAL | kthread: consolidate kthread exit paths to prevent use-after-free |
| CVE-2026-43379 | 9.8 CRITICAL | ksmbd: fix use-after-free in smb_lazy_parent_lease_break_close() |
| CVE-2026-43465 | 9.8 CRITICAL | net/mlx5e: RX, Fix XDP multi-buf frag counting for striding RQ |
| CVE-2026-43384 | 9.8 CRITICAL | net/tcp-ao: Fix MAC comparison to be constant-time |
| CVE-2026-43383 | 9.4 CRITICAL | net/tcp-md5: Fix MAC comparison to be constant-time |
| CVE-2026-43407 | 9.1 CRITICAL | libceph: Fix potential out-of-bounds access in ceph_handle_auth_reply() |
| CVE-2026-43406 | 9.1 CRITICAL | libceph: prevent potential out-of-bounds reads in process_message_header() |
| CVE-2026-43284 | 8.8 HIGH | xfrm: esp: avoid in-place decrypt on shared skb frags |
| CVE-2026-43334 | 8.8 HIGH | Bluetooth: SMP: force responder MITM requirements before building the pairing response |
| CVE-2026-43403 | 8.8 HIGH | nsfs: tighten permission checks for ns iteration ioctls |
| CVE-2026-43322 | 8.8 HIGH | Bluetooth: hci_sync: Fix UAF in le_read_features_complete |
| CVE-2026-43391 | 8.8 HIGH | nsfs: tighten permission checks for handle opening |
| CVE-2026-43291 | 8.3 HIGH | net: nfc: nci: Fix parameter validation for packet data |
| CVE-2026-43466 | 8.2 HIGH | net/mlx5e: Fix DMA FIFO desync on error CQE SQ recovery |
| CVE-2026-43452 | 8.2 HIGH | netfilter: x_tables: guard option walkers against 1-byte tail reads |
| CVE-2026-43365 | 8.2 HIGH | xfs: fix undersized l_iclog_roundoff values |
Showing top 20 of 199 CVEs. View all on vendor page → →
IV. Related Vulnerabilities
Same product: Linux
- CVE-2026-43500
rxrpc: Also unshare DATA/RESPONSE packets when paged frags a - CVE-2026-43475
scsi: storvsc: Fix scheduling while atomic on PREEMPT_RT - CVE-2026-43474
fs: init flags_valid before calling vfs_fileattr_get - CVE-2026-43473
scsi: mpi3mr: Add NULL checks when resetting request and rep - CVE-2026-43472
unshare: fix unshare_fs() handling
Same vendor: Linux
- CVE-2026-43500
rxrpc: Also unshare DATA/RESPONSE packets when paged frags a - CVE-2026-43475
scsi: storvsc: Fix scheduling while atomic on PREEMPT_RT - CVE-2026-43474
fs: init flags_valid before calling vfs_fileattr_get - CVE-2026-43473
scsi: mpi3mr: Add NULL checks when resetting request and rep - CVE-2026-43472
unshare: fix unshare_fs() handling
V. Comments for CVE-2026-43418
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