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CVE-2026-64121

Vulnerability intelligence

Published Jul 19, 2026Sources checked Oct 27, 2026
7.1HIGHCVSS out of 10
What this means

Review the available evidence

CVE-2026-64121 and is rated High severity with a CVSS score of 7.1. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Ubuntu Security Notices guidance

Vendor revision: Sep 29, 2026
Vendor remediation details

This update corrects flaws in the following subsystems: - ARM32 architecture; - ARM64 architecture; - PowerPC architecture; - Compute Acceleration Framework; - Drivers core; - Bluetooth drivers; - Arm Firmware Framework for ARMv8-A(FFA); - EFI core; - GPU drivers; - Hardware monitoring drivers; - InfiniBand drivers; - Network drivers; - Microsoft Azure Network Adapter (MANA) driver; - SCSI subsystem; - SPI subsystem; - Network file systems library; - NTFS3 file system; - SMB network file system; - File systems infrastructure; - Software nodes and device properties; - Bluetooth subsystem; - Netfilter; - Tracing infrastructure; - io_uring subsystem; - IRQ subsystem; - KProbes tracing; - Memory management; - B.A.T.M.A.N.

Ubuntu Security Notices guidance

Vendor revision: Sep 25, 2026
Vendor remediation details

This update corrects flaws in the following subsystems: - ARM32 architecture; - ARM64 architecture; - PowerPC architecture; - Compute Acceleration Framework; - Drivers core; - Bluetooth drivers; - Arm Firmware Framework for ARMv8-A(FFA); - EFI core; - GPU drivers; - Hardware monitoring drivers; - InfiniBand drivers; - Network drivers; - Microsoft Azure Network Adapter (MANA) driver; - SCSI subsystem; - SPI subsystem; - Network file systems library; - NTFS3 file system; - SMB network file system; - File systems infrastructure; - Software nodes and device properties; - Bluetooth subsystem; - Netfilter; - Tracing infrastructure; - io_uring subsystem; - IRQ subsystem; - KProbes tracing; - Memory management; - B.A.T.M.A.N.

Ubuntu Security Notices guidance

Vendor revision: Sep 22, 2026
Vendor remediation details

This update corrects flaws in the following subsystems: - ARM32 architecture; - ARM64 architecture; - PowerPC architecture; - Compute Acceleration Framework; - Drivers core; - Bluetooth drivers; - Arm Firmware Framework for ARMv8-A(FFA); - EFI core; - GPU drivers; - Hardware monitoring drivers; - InfiniBand drivers; - Network drivers; - Microsoft Azure Network Adapter (MANA) driver; - SCSI subsystem; - SPI subsystem; - Network file systems library; - NTFS3 file system; - SMB network file system; - File systems infrastructure; - Software nodes and device properties; - Bluetooth subsystem; - Netfilter; - Tracing infrastructure; - io_uring subsystem; - IRQ subsystem; - KProbes tracing; - Memory management; - B.A.T.M.A.N.

CISA KEVNot listedBased on the latest collected catalog
EPSS0.1%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview

What is CVE-2026-64121?

In the Linux kernel, the following vulnerability has been resolved:

net: ifb: report ethtool stats over num_tx_queues

ifb_dev_init() allocates dp->tx_private to dev->num_tx_queues entries via kzalloc_objs(*txp, dev->num_tx_queues). Both IFB per-queue RX and TX stats live in those entries: ifb_xmit() updates txp->rx_stats using the skb queue mapping, ifb_ri_tasklet() updates txp->tx_stats, and ifb_stats64() aggregates both over dev->num_tx_queues.

The ethtool stats callbacks instead size and walk the per-queue stats with dev->real_num_rx_queues and dev->real_num_tx_queues. With an asymmetric device where the RX queue count exceeds the TX queue count, for example:

ip link add name ifb10 numtxqueues 1 numrxqueues 8 type ifb ethtool -S ifb10

ifb_get_ethtool_stats() indexes past the tx_private allocation and copies adjacent slab data through ETHTOOL_GSTATS.

Use dev->num_tx_queues consistently for the stats strings, the stats count, and the stats data walks. This reports one RX stats group and one TX stats group for each backing ifb_q_private entry, which is the queue set IFB can actually populate.

Reproduced under UML+KASAN at v7.1-rc2:

BUG: KASAN: slab-out-of-bounds in ifb_fill_stats_data+0x3c/0xae Read of size 8 at addr 0000000062dbd228 by task ethtool/36 ifb_fill_stats_data+0x3c/0xae ifb_get_ethtool_stats+0xc0/0x129 __dev_ethtool+0x1ca5/0x363c dev_ethtool+0x123/0x1b3 dev_ioctl+0x56c/0x744 sock_do_ioctl+0x15f/0x1b2 sock_ioctl+0x4d5/0x50a sys_ioctl+0xd8b/0xde9

With the patch applied, the same UML+KASAN repro is silent and ethtool -S ifb10 reports only the stats backed by the single allocated tx_private entry.

Source: NVD