CyberSecBulletin
CVE-2026-43466NVD status: Modified

Linux: Improper Synchronization

Published Updated By the CyberSecBulletin desk

CVE-2026-43466 is a high-severity improper synchronization vulnerability in Linux, with a CVSS 3.1 base score of 8.2 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 821f85d619f7f22cda7b9d7de89cf5eeb1d11544, 6eb68ecc5acc3b319986566c595990b8a7265b23, 6f41f7812bfa7f991b732a4b45c5c52fc4be3b4e as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.41% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 821f85d619f7f22cda7b9d7de89cf5eeb1d11544 or 6eb68ecc5acc3b319986566c595990b8a7265b23 or 6f41f7812bfa7f991b732a4b45c5c52fc4be3b4e or 383b37c04a4827ba60b2bafc1a6cdfd995aed58f, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.253 or 5.15.203 or 6.1.167 or 6.6.130, whichever matches your release line, or a later version.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxdb75373c91b0cfb6a68ad6ae88721e4e21ae6261 up to, but not including, 821f85d619f7f22cda7b9d7de89cf5eeb1d11544; db75373c91b0cfb6a68ad6ae88721e4e21ae6261 up to, but not including, 6eb68ecc5acc3b319986566c595990b8a7265b23; db75373c91b0cfb6a68ad6ae88721e4e21ae6261 up to, but not including, 6f41f7812bfa7f991b732a4b45c5c52fc4be3b4e; db75373c91b0cfb6a68ad6ae88721e4e21ae6261 up to, but not including, 383b37c04a4827ba60b2bafc1a6cdfd995aed58f; db75373c91b0cfb6a68ad6ae88721e4e21ae6261 up to, but not including, 9c5ee9b981ee050b73fdf3f4a2464d6f1a8e10a8; db75373c91b0cfb6a68ad6ae88721e4e21ae6261 up to, but not including, ce1b19dd0684eeb68a124c11085bd611260b36d9; db75373c91b0cfb6a68ad6ae88721e4e21ae6261 up to, but not including, 829efcccfa8f69db5dc8332961295587d218cee6; db75373c91b0cfb6a68ad6ae88721e4e21ae6261 up to, but not including, 1633111d69053512d099658d4a05fc736fab36b0; and 1 more ranges821f85d619f7f22cda7b9d7de89cf5eeb1d11544, 6eb68ecc5acc3b319986566c595990b8a7265b23, 6f41f7812bfa7f991b732a4b45c5c52fc4be3b4e, 383b37c04a4827ba60b2bafc1a6cdfd995aed58f, 9c5ee9b981ee050b73fdf3f4a2464d6f1a8e10a8, ce1b19dd0684eeb68a124c11085bd611260b36d9
LinuxLinux Kernel4.17 up to, but not including, 5.10.253; 5.11 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.167; 6.2 up to, but not including, 6.6.130; 6.7 up to, but not including, 6.12.78; 6.13 up to, but not including, 6.18.19; 6.19 up to, but not including, 6.19.9; 7.05.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.19

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
LowLimited modification of data is possible.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: Fix DMA FIFO desync on error CQE SQ recovery In case of a TX error CQE, a recovery flow is triggered, mlx5e_reset_txqsq_cc_pc() resets dma_fifo_cc to 0 but not dma_fifo_pc, desyncing the DMA FIFO producer and consumer. After recovery, the producer pushes new DMA entries at the old dma_fifo_pc, while the consumer reads from position 0. This causes us to unmap stale DMA addresses from before the recovery. The DMA FIFO is a purely software construct with no HW counterpart. At the point of reset, all WQEs have been flushed so dma_fifo_cc is already equal to dma_fifo_pc. There is no need to reset either counter, similar to how skb_fifo pc/cc are untouched. Remove the 'dma_fifo_cc = 0' reset. This fixes the following WARNING: WARNING: CPU: 0 PID: 0 at drivers/iommu/dma-iommu.c:1240 iommu_dma_unmap_page+0x79/0x90 Modules linked in: mlx5_vdpa vringh vdpa bonding mlx5_ib mlx5_vfio_pci ipip mlx5_fwctl tunnel4 mlx5_core ib_ipoib geneve ip6_gre ip_gre gre nf_tables ip6_tunnel rdma_ucm ib_uverbs ib_umad vfio_pci vfio_pci_core act_mirred act_skbedit act_vlan vhost_net vhost tap ip6table_mangle ip6table_nat ip6table_filter ip6_tables iptable_mangle cls_matchall nfnetlink_cttimeout act_gact cls_flower sch_ingress vhost_iotlb iptable_raw tunnel6 vfio_iommu_type1 vfio openvswitch nsh rpcsec_gss_krb5 auth_rpcgss oid_registry xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink iptable_nat nf_nat xt_addrtype br_netfilter overlay zram zsmalloc rpcrdma ib_iser libiscsi scsi_transport_iscsi rdma_cm iw_cm ib_cm ib_core fuse [last unloaded: nf_tables] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.13.0-rc5_for_upstream_min_debug_2024_12_30_21_33 #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:iommu_dma_unmap_page+0x79/0x90 Code: 2b 4d 3b 21 72 26 4d 3b 61 08 73 20 49 89 d8 44 89 f9 5b 4c 89 f2 4c 89 e6 48 89 ef 5d 41 5c 41 5d 41 5e 41 5f e9 c7 ae 9e ff <0f> 0b 5b 5d 41 5c 41 5d 41 5e 41 5f c3 66 2e 0f 1f 84 00 00 00 00 Call Trace: <IRQ> ? __warn+0x7d/0x110 ? iommu_dma_unmap_page+0x79/0x90 ? report_bug+0x16d/0x180 ? handle_bug+0x4f/0x90 ? exc_invalid_op+0x14/0x70 ? asm_exc_invalid_op+0x16/0x20 ? iommu_dma_unmap_page+0x79/0x90 ? iommu_dma_unmap_page+0x2e/0x90 dma_unmap_page_attrs+0x10d/0x1b0 mlx5e_tx_wi_dma_unmap+0xbe/0x120 [mlx5_core] mlx5e_poll_tx_cq+0x16d/0x690 [mlx5_core] mlx5e_napi_poll+0x8b/0xac0 [mlx5_core] __napi_poll+0x24/0x190 net_rx_action+0x32a/0x3b0 ? mlx5_eq_comp_int+0x7e/0x270 [mlx5_core] ? notifier_call_chain+0x35/0xa0 handle_softirqs+0xc9/0x270 irq_exit_rcu+0x71/0xd0 common_interrupt+0x7f/0xa0 </IRQ> <TASK> asm_common_interrupt+0x22/0x40

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Synchronization

The product utilizes multiple threads, processes, components, or systems to allow temporary access to a shared resource that can only be exclusive to one process at a time, but it does not properly synchronize these actions, which might cause simultaneous accesses of this resource by multiple threads or processes.

How developers prevent this class of flaw

  • Use industry standard APIs to synchronize your code.

More Improper Synchronization vulnerabilities (CWE-662)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Improper Synchronization vulnerabilities

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