Insufficient headroom in Linux kernel VLAN header handling
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
- —
- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 7 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
The Linux kernel is affected from 2.6.12 before the fixed versions listed in the solution. In vlan_dev_hard_header(), socket buffers with too little headroom, such as those allocated before device headroom changed, trigger skb_under_panic. Callers that reserve only ETH_HLEN or less, such as llc_alloc_frame(), can also reach this path.
Written with Claude Haiku 5.5 from the sources below · 2026-10-30
Description from the CNA
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.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 2.6.12 and later | 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9, 7.3 | Patch available | CNA |
- Linux VendorLinux Affected 2.6.12 and later 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 Patch available CNA
Remediation
Update the Linux kernel to 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9 or 7.3, or to a release that includes the fixing commits. Red Hat Enterprise Linux 6 has no fix planned. Red Hat Enterprise Linux 7, 8, 9 and 10 and Red Hat OpenShift Container Platform 4 and 5 have no fix available.
Written with Claude Haiku 5.5 from the sources below · 2026-10-30
- Fix · CNA Linux (Linux) 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
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-18 Threatist record created from CVE-2026-98554
- 2026-10-18 Alias added: GHSA-xh57-3wrj-366f
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-20 Affected versions changed · Red Hat
- 2026-10-20 CVSS score added · Red Hat
- 2026-10-30 Affected versions changed · Red Hat
References
Other 8
- https://git.kernel.org/stable/c/55e007fc3b4d76fa4d6b4660f6904fe6ab045a1b
- https://git.kernel.org/stable/c/5aca8e6a8ff6aeae358c1d9b65447aac416ace95
- https://git.kernel.org/stable/c/4ba1f57313f36a3ce6f77d593548f0c511f34aa1
- https://git.kernel.org/stable/c/ca797491f0ae4bfde9039f79f6f1ed7781c9110f
- https://git.kernel.org/stable/c/cfba0f45553de2b803059e3d539a1e418df24da8
- https://git.kernel.org/stable/c/c7ee4bea64f559ea8e03260014775b64c720cb5b
- https://git.kernel.org/stable/c/90d51095371d96747f45bbd8504edf6513e039ef
- https://git.kernel.org/stable/c/cd5dd68267c4238795fadaf02b3575ca3f8a6500
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Sources
- CVE-2026-98554 · CVE Program
- CVE-2026-98554 · NVD
- FIRST EPSS
- GHSA-xh57-3wrj-366f · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98554 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences