CVE-2026-46273
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.39%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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).
- CVSS 3.1
- 8.6 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
- EPSS
- 0.39% probability · 32th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-400
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/1cdf5dbcec988d06f5f720bdf89e91073f77fa10Patch
- https://git.kernel.org/stable/c/3af24f0c4c31f18a4a2d927990759194832bb6e9Patch
- https://git.kernel.org/stable/c/82bc89fbb82d9396fb4eaee8720ea85e2e787957Patch
- https://git.kernel.org/stable/c/86fc64584811d43c9ccd74447de58620189d8b77Patch
- https://git.kernel.org/stable/c/9a5e984d7af910e46dcbed3ce77873e000a4f77dPatch
- https://git.kernel.org/stable/c/c1f261863e65b508f37416dfbc5c5d911c9b9233Patch
- https://git.kernel.org/stable/c/cc427d24ac6442ffdeafd157a63c7c5b73ed4de4Patch
- https://git.kernel.org/stable/c/db8012c631cb845e9ae2b4b531e17d86c9519755Patch
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.