Linux Kernel up to 7.2.8/7.3-rc4 fbnic fbnic_queue_mem_alloc use after free

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.2.8/7.3-rc4. It has been rated as very critical. Impacted is the function fbnic_queue_mem_alloc of the component fbnic. Performing a manipulation results in use after free. This vulnerability was named CVE-2026-98617. The attack needs to be approached locally. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as very critical has been found in Linux Kernel up to 7.2.8/7.3-rc4. This affects the function fbnic_queue_mem_alloc of the component fbnic. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: eth: fbnic: use the Rx queue napi pointer to find the napi vector The queue management ndos pick the napi vector for an Rx queue with: nv = fbn->napi[idx % fbn->num_napi]; The issue is this is only correct in the cases where there are no standalone Tx vectors. In those cases we were allocating the Tx vectors first and then the Rx so the queues would be pointing to Tx NAPI vectors instead of the Rx ones. The mapping the ndos want is already recorded. fbnic_set_netif_napi() publishes it with netif_queue_set_napi(), which stores the napi pointer in netdev_rx_queue.napi, and fbnic_reset_netif_napi() clears it again. Both run under the netdev instance lock that the queue management ndos also hold, so the pointer can be read directly. Use it and drop the divide. The pointer is NULL exactly while the datapath is down, so fbnic_queue_mem_alloc() can reject that case rather than reaching into freed state: netdev_rx_queue_restart() calls it before it tests netif_running(), and fbnic_pm_suspend() leaves netif_running() true across a PCIe recovery that never completes, so a queue restart can arrive after fbnic_stop() has freed the rings and the vectors. fbnic_stop() clears the association in fbnic_reset_netif_queues() before fbnic_free_napi_vectors(), so the NULL is always published first. fbnic_queue_start() and fbnic_queue_stop() need no check of their own, as netdev_rx_queue_reconfig() only reaches them once fbnic_queue_mem_alloc() has succeeded under the same instance lock.

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-98617 since 09/25/2026. The exploitability is told to be easy. Attacking locally is a requirement. Additional levels of successful authentication are necessary for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/18/2026).

Upgrading to version 7.2.9 or 7.3-rc5 eliminates this vulnerability. Applying the patch 1fb569cf3bf97e552f465b2c719e36b48ae7c18b/b5d9e9d4d0c13bc8b60d8d97e7a07fb25fea639e is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5
• 7.2.6
• 7.2.7
• 7.2.8
• 7.3-rc1
• 7.3-rc2
• 7.3-rc3
• 7.3-rc4

License

• open-source

Website

• Vendor: https://www.kernel.org/

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