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CVE.org (no NVD analysis yet)· CNA Linux

CVE-2026-98554: vlan: ensure sufficient headroom in vlan_dev_hard_header()

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.21% (FIRST EPSS).
  • Fixed version: Linux Linux 4ba1f57313f36a3ce6f77d593548f0c511f34aa1, 55e007fc3b4d76fa4d6b4660f6904fe6ab045a1b, 5aca8e6a8ff6aeae358c1d9b65447aac416ace95; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.159.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 4ba1f57313f36a3ce6f77d593548f0c511f34aa1, 55e007fc3b4d76fa4d6b4660f6904fe6ab045a1b, 5aca8e6a8ff6aeae358c1d9b65447aac416ace95; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.159.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

—No exploit Fix available
Published
Oct 18, 2026
Updated
Oct 19, 2026
EPSS
0.2% · 12th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

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  • No public exploit code on record
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.12affected
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 55e007fc3b4d76fa4d6b4660f6904fe6ab045a1baffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 5aca8e6a8ff6aeae358c1d9b65447aac416ace95affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 4ba1f57313f36a3ce6f77d593548f0c511f34aa1affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before ca797491f0ae4bfde9039f79f6f1ed7781c9110faffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before cfba0f45553de2b803059e3d539a1e418df24da8affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before c7ee4bea64f559ea8e03260014775b64c720cb5baffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 90d51095371d96747f45bbd8504edf6513e039efaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before cd5dd68267c4238795fadaf02b3575ca3f8a6500affected · git
    • before 2.6.12not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.190-16.1.190-1
Debian:12linux-6.12before 6.12.113-1~deb12u16.12.113-1~deb12u1
Debian:13linuxbefore 6.12.113-16.12.113-1
Debian:14linuxbefore 7.2.9-17.2.9-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-98552Oct 18, 2026 · perf/core: Fix a refcount leak in attach_perf_ctx_data()
    0Monitor
  • ← EarlierCVE-2026-98553Oct 18, 2026 · autofs: fix sbi->pipe file reference leak in autofs_kill_sb()
    0Monitor
  • Later →CVE-2026-98555Oct 18, 2026 · llc: fix skb UAF and leaks on llc_mac_hdr_init() failure
    30Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux4ba1f57313f36a3ce6f77d593548f0c511f34aa1Vendor (CNA)
Linux Linux55e007fc3b4d76fa4d6b4660f6904fe6ab045a1bVendor (CNA)
Linux Linux5aca8e6a8ff6aeae358c1d9b65447aac416ace95Vendor (CNA)
Linux Linux90d51095371d96747f45bbd8504edf6513e039efVendor (CNA)
Linux Linuxc7ee4bea64f559ea8e03260014775b64c720cb5bVendor (CNA)
Linux Linuxca797491f0ae4bfde9039f79f6f1ed7781c9110fVendor (CNA)
Linux Linuxcd5dd68267c4238795fadaf02b3575ca3f8a6500Vendor (CNA)
Linux Linuxcfba0f45553de2b803059e3d539a1e418df24da8Vendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.06.6.159.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.1.190-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.113-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 5, 2026+17 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Exploit maturity— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records