Linux Kernel up to 7.2.6/7.3-rc2 bnxt_en bnxt_txr_db_kick denial of service

Summaryinfo

A vulnerability identified as critical has been detected in Linux Kernel up to 7.2.6/7.3-rc2. Impacted is the function bnxt_txr_db_kick of the component bnxt_en. This manipulation causes denial of service. This vulnerability is handled as CVE-2026-97569. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 7.2.6/7.3-rc2. Affected by this vulnerability is the function bnxt_txr_db_kick of the component bnxt_en. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: bnxt_en: Prevent queue stop with deferred completions When the driver receives a burst of packets, it can mark a BD with the NO_CMPL bit to defer completions. The expectation is that the last packet in the ring will have this bit unset and the completion generated by that packet will cleanup that packet and the ones preceding it. This helps to reduce the number of completions fired. The suppressed completions are controlled by the driver and the number of packets with suppressed completions scales with the size of the ring. SW USO packets, on the other hand, have an upper bound on the maximum number of BDs which can be consumed which does not scale with the ring size. So, for small rings it is possible that: a burst of packets is handed to the driver, the driver defers completions for all of the packets because the number of free descriptors stays above the threshold in the driver. Then, a USO packet arrives, but the number of BDs available is not enough and the USO code exits early. In this case, you end up in a state where the ring is full of packets with their completions suppressed, which can cause the queue to stop and never be restarted. Assuming default CONFIG_MAX_SKB_FRAGS, this is only possible for small rings (<= 457 descriptors, below the driver default value) when a burst of packets fills the ring, followed by a large USO packet that can't fit. For larger rings, the delta between the completion suppression threshold and the BDs required for SW USO is large enough that completions will fire and this case is unreachable. This issue was pointed out by Sashiko and while it seems fairly unlikely given that the queue size must be small to trigger this, it is indeed possible. Fix this by tracking the last BD which deferred completions and centralizing the logic for deciding when to ring the doorbell. The NO_CMPL bit is now cleared in bnxt_txr_db_kick(), so every doorbell site is covered, including the SW USO early exit. This guarantees the ring always ends in a BD which generates a completion to clean it and wake the queue.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-97569 since 09/24/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/25/2026). MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 7.2.7 or 7.3-rc3 eliminates this vulnerability. Applying the patch e33ce547c0cd40738d6bad23e5fc0539ee3e8f7d/39b23c1c40e1f73d2b94a09282cc476af647e438 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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
• 7.3-rc1
• 7.3-rc2

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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