CVE-2026-93830: In the Linux kernel, the following vulnerability has been resolved: net: stmmac: xgmac2: disable RBUE in default RX interrupt mask Enabling the RX Buffer Unav

In the Linux kernel, the following vulnerability has been resolved: net: stmmac: xgmac2: disable RBUE in default RX interrupt mask Enabling the RX Buffer Unav

In the Linux kernel, the following vulnerability has been resolved: net: stmmac: xgmac2: disable RBUE in default RX interrupt mask Enabling the RX Buffer Unavailable (RBUE) interrupt is counterproductive and can trigger a MAC interrupt storm under heavy RX pressure. When the DMA runs out of RX descriptors it fires RBUE continuously until software refills the ring. However, RBUE is redundant: the normal RX completion interrupt (RIE) already triggers NAPI, which processes completed descriptors and refills the ring, causing the DMA to resume. The RBUE handler itself only sets handle_rx - the same outcome as RIE. On Agilex5 under heavy RX pressure, the MAC interrupt (which includes RBUE) was observed firing 1,821,811,555 times against only 2,618,627 actual RX completions - a ~695x ratio - confirming the severity of the storm. RBUE does not provide OOM recovery. If page_pool is exhausted, stmmac_rx_refill() cannot advance the DMA tail pointer, the DMA stays suspended, and RBUE fires again on the next NAPI completion - a storm with no forward progress. This patch trades that storm for a clean stall with the same RX outcome. Proper OOM recovery is a pre-existing gap outside the scope

Description from the National Vulnerability Database, published by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

What it means for a small business

Linux is on the computers, phones or browsers your team uses every day. Turn on automatic updates and restart: most of these fixes only take effect after a restart.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.49%, higher than 42% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 29, 2026, updated daily.

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Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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