CVE-2026-46273
HighCVSS 8.6Exploitation Probability (EPSS)
Low risk32th percentile - higher than 32% of all known CVEs
Summary
In the Linux kernel, the ibmveth driver has an issue with GSO segmentation for packets with small MSS (below 224 bytes). Attempting to send such packets freezes the adapter, stopping all traffic until manual reset.
Risk Assessment
This vulnerability can cause network outages on Power systems, leading to unavailability of network services.
Recommendation
Apply the Linux kernel patch that adds ndo_features_check to disable GSO for packets with MSS < 224 bytes.
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: ibmveth: Disable GSO for packets with small MSS Some physical adapters on Power systems do not support segmentation offload when the MSS is less than 224 bytes. Attempting to send such packets causes the adapter to freeze, stopping all traffic until manually reset. Implement ndo_features_check to disable GSO for packets with small MSS values. The network stack will perform software segmentation instead. The 224-byte minimum matches ibmvnic commit <f10b09ef687f> ("ibmvnic: Enforce stronger sanity checks on GSO packets") which uses the same physical adapters in SEA configurations. The issue occurs specifically when the hardware attempts to perform segmentation (gso_segs > 1) with a small MSS. Single-segment GSO packets (gso_segs == 1) do not trigger the problematic LSO code path and are transmitted normally without segmentation. Add an ndo_features_check callback to disable GSO when MSS < 224 bytes. Also call vlan_features_check() to ensure proper handling of VLAN packets, particularly QinQ (802.1ad) configurations where the hardware parser may not support certain offload features. Validated using iptables to force small MSS values. Without the fix, the adapter freezes. With the fix, packets are segmented in software and transmission succeeds. Comprehensive regression testing completedd (MSS tests, performance, stability).
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

