{"cve":"CVE-2026-46273","nvd":{"published":"2026-06-03T18:16:29.160","modified":"2026-08-07T13:16:49.260","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nibmveth: Disable GSO for packets with small MSS\n\nSome physical adapters on Power systems do not support segmentation\noffload when the MSS is less than 224 bytes. Attempting to send such\npackets causes the adapter to freeze, stopping all traffic until\nmanually reset.\n\nImplement ndo_features_check to disable GSO for packets with small MSS\nvalues. The network stack will perform software segmentation instead.\n\nThe 224-byte minimum matches ibmvnic\ncommit <f10b09ef687f> (\"ibmvnic: Enforce stronger sanity checks\non GSO packets\")\nwhich uses the same physical adapters in SEA configurations.\n\nThe issue occurs specifically when the hardware attempts to perform\nsegmentation (gso_segs > 1) with a small MSS. Single-segment GSO packets\n(gso_segs == 1) do not trigger the problematic LSO code path and are\ntransmitted normally without segmentation.\n\nAdd an ndo_features_check callback to disable GSO when MSS < 224 bytes.\nAlso call vlan_features_check() to ensure proper handling of VLAN packets,\nparticularly QinQ (802.1ad) configurations where the hardware parser may\nnot support certain offload features.\n\nValidated using iptables to force small MSS values. Without the fix,\nthe adapter freezes. With the fix, packets are segmented in software\nand transmission succeeds. Comprehensive regression testing completedd\n(MSS tests, performance, stability).","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H","score":8.6},"cwes":["CWE-400"],"references":["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"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:37:48.043517290+00:00"},"epss":{"cve":"CVE-2026-46273","score":0.00389,"percentile":0.33003,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}