CVE-2026-46273

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 v3.1 Score

8.6

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0039

Probability of exploitation

0.31%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Affected Products

Vendor	Product	Versions
linux	linux_kernel	4.2 — 5.10.258
linux	linux_kernel	5.11 — 5.15.209
linux	linux_kernel	5.16 — 6.1.175
linux	linux_kernel	6.2 — 6.6.140
linux	linux_kernel	6.7 — 6.12.88
linux	linux_kernel	6.13 — 6.18.30
linux	linux_kernel	6.19 — 7.0.7
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/1cdf5dbcec988d06f5f720bdf89e91073f77fa10 https://git.kernel.org/stable/c/3af24f0c4c31f18a4a2d927990759194832bb6e9 https://git.kernel.org/stable/c/82bc89fbb82d9396fb4eaee8720ea85e2e787957 https://git.kernel.org/stable/c/86fc64584811d43c9ccd74447de58620189d8b77 https://git.kernel.org/stable/c/9a5e984d7af910e46dcbed3ce77873e000a4f77d https://git.kernel.org/stable/c/c1f261863e65b508f37416dfbc5c5d911c9b9233 https://git.kernel.org/stable/c/cc427d24ac6442ffdeafd157a63c7c5b73ed4de4 https://git.kernel.org/stable/c/db8012c631cb845e9ae2b4b531e17d86c9519755

Frequently Asked Questions

What is 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. 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). It has a CVSS v3.1 base score of 8.6 (HIGH).

How severe is CVE-2026-46273? +

CVE-2026-46273 has a CVSS v3.1 score of 8.6 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0039, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-46273? +

CVE-2026-46273 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-46273? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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