CVE-2026-98554
In the Linux kernel, the following vulnerability has been resolved: vlan: ensure sufficient headroom in vlan_dev_hard_header() Callers that only reserve ETH_HLEN or less (such as llc_alloc_frame()), or skbs allocated before dynamic device/headroom changes (e.g. toggling VLAN_FLAG_REORDER_HDR or bonding/team switching slaves), can reach vlan_dev_hard_header() with insufficient headroom and trigger skb_under_panic(). Use skb_cow_head() in vlan_dev_hard_header() when VLAN_FLAG_REORDER_HDR is not set to ensure sufficient headroom for the VLAN header(s) and the underlying device hard header. Use READ_ONCE() to read dev->hard_header_len and dev->needed_headroom as they can be updated concurrently under RTNL (e.g. in vlan_transfer_features()) while vlan_dev_hard_header() runs locklessly on the transmit path. Also avoid LL_RESERVED_SPACE(dev) here so that the extra HH_DATA_MOD alignment padding does not trigger unnecessary pskb_expand_head() reallocations on inner stacked VLAN devices after the outer VLAN header has been pushed.
Affected versions
Linux kernel versions
2.6.12
and later are affected. Fixed in
5.10.271,
5.15.222,
6.1.189,
6.6.158,
6.12.112,
6.18.55,
7.2.9,
7.3
and their respective stable series.
References
8 totalFrequently asked questions
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What is CVE-2026-98554?
CVE-2026-98554 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 2.6.12 onward and has been patched in 5.10.271, 5.15.222, 6.1.189 and others. CVE-2026-98554 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-98554?
Yes. CVE-2026-98554 has been patched. Fixed versions include 5.10.271, 5.15.222, 6.1.189 and others. If you are running Linux kernel 2.6.12 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-98554 actively exploited?
No. CVE-2026-98554 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.