Linux Kernel up to 7.1.4 RX Queue nk_qlease.py netif_rxq_cleanup_unlease use after free

Summaryinfo

A vulnerability identified as very critical has been detected in Linux Kernel up to 7.1.4. Affected by this issue is the function netif_rxq_cleanup_unlease of the file nk_qlease.py of the component RX Queue. This manipulation causes use after free. The identification of this vulnerability is CVE-2026-74285. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as very critical was found in Linux Kernel up to 7.1.4. Affected by this vulnerability is the function netif_rxq_cleanup_unlease of the file nk_qlease.py of the component RX Queue. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: net: Stop leased rxq before uninstalling its memory provider netif_rxq_cleanup_unlease() tears down the memory provider that was installed on a physical RX queue through a netkit queue lease. It currently revokes the provider's DMA mappings before stopping the physical queue: __netif_mp_uninstall_rxq(virt_rxq, p); /* DMA unmap */ __netif_mp_close_rxq(phys_rxq->dev, rxq_idx, p); /* queue stop */ This inverts the ordering used by the regular teardown paths (normal device unregister and the io_uring zcrx close path), which stop the queue before revoking the provider's mappings. With the physical queue still live, its NAPI can keep consuming net_iov entries from the page_pool alloc cache after the __netif_mp_uninstall_rxq() has already cleared their dma_addr, opening a window for the device to DMA to a stale or zero address. Fix it by swapping the two calls so the queue is stopped (and its NAPI quiesced) before the provider is uninstalled. No functional regression was observed across repeated runs of the nk_qlease.py HW selftest, which exercises the lease teardown path; this was tested against fbnic QEMU emulation.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-74285 since 08/15/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 08/15/2026).

Upgrading to version 7.1.5 or 7.2-rc1 eliminates this vulnerability. Applying the patch 03f4c6ed3cffbfce0b85a3a0193d08a46692a9f8/37314c9dbe95b4d924c7b61aaf563cec4f4e4133 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.4

License

• open-source

Website

• Vendor: https://www.kernel.org/

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