{"id":"CVE-2026-93830","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: stmmac: xgmac2: disable RBUE in default RX interrupt mask\n\nEnabling the RX Buffer Unavailable (RBUE) interrupt is counterproductive\nand can trigger a MAC interrupt…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: stmmac: xgmac2: disable RBUE in default RX interrupt mask\n\nEnabling the RX Buffer Unavailable (RBUE) interrupt is counterproductive\nand can trigger a MAC interrupt…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","vendor":"Linux","product":"Linux","affected":["Linux >= d6ddfacd95c79d43465d4a85dffb1c9beca343a9 < 8c9d57b5dc098b84631d0b3559c84c499ea2170a","Linux >= d6ddfacd95c79d43465d4a85dffb1c9beca343a9 < 7a10e54e42a8f73a8d731f5a281fc06bb41b9250","Linux >= d6ddfacd95c79d43465d4a85dffb1c9beca343a9 < 6b3b91433d5f4eae6865cdaa96f40cd67849e1f6","Linux >= d6ddfacd95c79d43465d4a85dffb1c9beca343a9 < 74dbb85a6a254b5fc1f265a6cd61b2ba9d9221d7","Linux >= d6ddfacd95c79d43465d4a85dffb1c9beca343a9 < 0b1a5d3647ce07c27a9fffefc11a8cbf7d7b25ce","Linux >= d6ddfacd95c79d43465d4a85dffb1c9beca343a9 < 87e2826ed2058747ddf014c082569a46bfadd96b","Linux >= d6ddfacd95c79d43465d4a85dffb1c9beca343a9 < d3265c19b35d036bba327b36b5366bee76b0157c","Linux 4.19"],"published":"2026-09-24","updated":"2026-10-03","sourceUpdated":"2026-10-03T11:17:52.673","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-93830","references":[{"url":"https://git.kernel.org/stable/c/0b1a5d3647ce07c27a9fffefc11a8cbf7d7b25ce","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6b3b91433d5f4eae6865cdaa96f40cd67849e1f6","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/74dbb85a6a254b5fc1f265a6cd61b2ba9d9221d7","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7a10e54e42a8f73a8d731f5a281fc06bb41b9250","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/87e2826ed2058747ddf014c082569a46bfadd96b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8c9d57b5dc098b84631d0b3559c84c499ea2170a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d3265c19b35d036bba327b36b5366bee76b0157c","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-93830.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-93830"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2540518"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-93830"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93830"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93830.mbox"}],"tags":["nvd","cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.0049,"epssPercentile":0.41924,"ingestedAt":"2026-09-24T16:47:15.889Z","cwe":["CWE-770"],"scores":{"nvd":7.5,"vendor":5.5},"slug":"CVE-2026-93830","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet: stmmac: xgmac2: disable RBUE in default RX interrupt mask\n\nEnabling the RX Buffer Unavailable (RBUE) interrupt is counterproductive\nand can trigger a MAC interrupt storm under heavy RX pressure. When the\nDMA runs out of RX descriptors it fires RBUE continuously until software\nrefills the ring.\n\nHowever, RBUE is redundant: the normal RX completion interrupt (RIE)\nalready triggers NAPI, which processes completed descriptors and refills\nthe ring, causing the DMA to resume. The RBUE handler itself only sets\nhandle_rx - the same outcome as RIE.\n\nOn Agilex5 under heavy RX pressure, the MAC interrupt (which includes\nRBUE) was observed firing 1,821,811,555 times against only 2,618,627\nactual RX completions - a ~695x ratio - confirming the severity of the\nstorm.\n\nRBUE does not provide OOM recovery. If page_pool is exhausted,\nstmmac_rx_refill() cannot advance the DMA tail pointer, the DMA stays\nsuspended, and RBUE fires again on the next NAPI completion - a storm\nwith no forward progress. This patch trades that storm for a clean\nstall with the same RX outcome. Proper OOM recovery is a pre-existing\ngap outside the scope of this fix.\n\nNote: as a consequence of disabling RBUE, the rx_buf_unav_irq ethtool\ncounter will always read 0 on XGMAC2 devices. This behaviour is already\ninconsistent across DWMAC core versions.\n\nRemove RBUE from XGMAC_DMA_INT_DEFAULT_EN and XGMAC_DMA_INT_DEFAULT_RX\nto prevent the interrupt storm while keeping normal RX handling intact.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-93830.json)","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":210571,"id":"CVE-2026-93830","ts":1790316054881,"field":"cvss","old":null,"new":"7.5"},{"seq":210570,"id":"CVE-2026-93830","ts":1790316054881,"field":"severity","old":"none","new":"high"}]}