Vulnerability in Linux kernel (CVE-2026-93830)
Summary
Vulnerability in Linux kernel (CVE-2026-93830). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
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 of this fix.
Note: as a consequence of disabling RBUE, the rx_buf_unav_irq ethtool
counter will always read 0 on XGMAC2 devices. This behaviour is already
inconsistent across DWMAC core versions.
Remove RBUE from XGMAC_DMA_INT_DEFAULT_EN and XGMAC_DMA_INT_DEFAULT_RX
to prevent the interrupt storm…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-93830 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-93830" on the vendor's site.
CVE-2026-93830 (Linux kernel) — CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (unclassified) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Ubuntu UBUNTU-CVE-2026-93830 linux
References
- advisory nvd.nist.gov
- advisory github.com
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web github.com