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CVE-2026-98377

vlan: require the MAC header to be present in __vlan_insert_inner_tag()

Products / packages Linux

Published

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Severity and exploitation

Not in CISA KEVNo CVSS score

KEV coverage does not rule out exploitation.

KEV checked 14/11/2026, 21:25:33 UTC

Severity

unknown

CVSS measures technical severity, not the likelihood of an attack.

Known exploitation

Not listed in the checked CISA KEV catalog

Absence from CISA KEV does not rule out attacks.

Public exploit

Not established by this record

Missing evidence does not mean no public exploit exists.

Remediation

Fix status not established

No structured fix or guidance is available here. Check the latest publisher advisory.

What this means

In the Linux kernel, the following vulnerability has been resolved:

Source excerpt · Linux

Attack conditions

vlan: require the MAC header to be present in __vlan_insert_inner_tag() Require the MAC header the helper rewrites to be present, so such a frame is dropped rather than transmitted.

Excerpt from the original source description below.

Review supporting sources →

Affected versions

Check the exact model, release, and any platform requirements against your installation.

Linux · Linux

Linux

8 ranges
Linux version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 → before 12295e0728488105b152b57fe8bc5e86f1d21a73

git versions

1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 → before aecace4ef31bd4e8ca1f224280ab52a457b0dc9a

git versions

1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 → before 50a958f865173e8752ff07bf0eff7b55cdeb5d74

git versions

1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 → before 3d531429524df2c7116579306640283fea68bcf0

git versions

1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 → before 40a5cc4b7251c74f3341332a226d02200e96bccf

git versions

1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 → before f42562dd027dc4ed103fae17b2206e73ea1963c4

git versions

1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 → before 59af43ccece4d2d8b62e9e3ccc96b6e2e793bcdc

git versions

1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 → before ab888242fce4f16f6c4d4c6ec53939ad36aa3b3a

git versions

unaffected

unknown

Other versions: unaffected

Linux · Linux

Linux

10 ranges
Linux version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

2.6.12

unaffected

0 → before 2.6.12

semver versions

5.10.273 → through 5.10.*

semver versions

5.15.224 → through 5.15.*

semver versions

6.1.191 → through 6.1.*

semver versions

6.6.160 → through 6.6.*

semver versions

6.12.112 → through 6.12.*

semver versions

6.18.55 → through 6.18.*

semver versions

7.2.9 → through 7.2.*

semver versions

7.3 → through *

original_commit_for_fix versions

unknown

Other versions: affected

Automatic dependency matching is unavailable for this record. Use the product evidence and publisher’s instructions to check your installation.

What to do

Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.

No structured fix or remediation guidance is available here. Check the full source description and vendor’s latest advisory for a patch or workaround; do not assume another version is safe.

cve.new guidance unless attributed to a publisher. This page does not inspect your installation.

Public exploit evidence

No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.

Original source description

Read the full publisher description

In the Linux kernel, the following vulnerability has been resolved:

vlan: require the MAC header to be present in __vlan_insert_inner_tag()

__vlan_insert_inner_tag() only guarantees head room via skb_cow_head(), never that mac_len bytes of MAC header are present. Its ETH_HLEN wrappers - __vlan_insert_tag() under skb_vlan_push(), and vlan_insert_tag() under validate_xmit_vlan() on the generic transmit path - therefore rewrite the first 16 bytes at skb->data: a 12-byte memmove plus two 2-byte stores at +12 and +14. No caller supplies the bound, while the pop helpers use skb_ensure_writable()/pskb_may_pull().

An IFF_TUN device has hard_header_len == 0, so packet_snd() accepts a one-byte AF_PACKET/SOCK_RAW frame. The first vlan push only sets a hwaccel tag; the next - clsact "action vlan push" or bpf_skb_vlan_push() - enters the helper with skb->len still 1. The head comes from skbuff_small_head without __GFP_ZERO, so each push drags bytes from beyond skb->tail into the frame. After three the one-byte send leaves as 13 bytes carrying 11 bytes of uninitialised slab:

0000: 5a b3 62 12 80 88 ff ff 00 b3 62 12 81 `------------------------------' only 0x5a was sent; the rest is slab, here the top 56 bits of a linear-map address

Require the MAC header the helper rewrites to be present, so such a frame is dropped rather than transmitted.

References

8 sources
git.kernel.org/stable/c/12295e0728488105b152b57fe8bc5e86f1d21a73
Source referenceLinux
git.kernel.org/stable/c/aecace4ef31bd4e8ca1f224280ab52a457b0dc9a
Source referenceLinux
git.kernel.org/stable/c/50a958f865173e8752ff07bf0eff7b55cdeb5d74
Source referenceLinux
git.kernel.org/stable/c/3d531429524df2c7116579306640283fea68bcf0
Source referenceLinux
git.kernel.org/stable/c/40a5cc4b7251c74f3341332a226d02200e96bccf
Source referenceLinux
git.kernel.org/stable/c/f42562dd027dc4ed103fae17b2206e73ea1963c4
Source referenceLinux
View 2 more references
git.kernel.org/stable/c/59af43ccece4d2d8b62e9e3ccc96b6e2e793bcdc
Source referenceLinux
git.kernel.org/stable/c/ab888242fce4f16f6c4d4c6ec53939ad36aa3b3a
Source referenceLinux

Inside the record

Evidence available

Package identity · not supplied
Version evidence
Remediation guidance · not supplied
Weakness classification · not supplied
Additional publishers · not supplied

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-98377

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Environment requirements

These conditions apply together as specified by the publisher. A matching product name alone does not establish exposure.

Linux · platform conditions

Any condition may hold

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 2.6.12

Before: 5.10.273

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 2.6.12

Before: 5.15.224

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 2.6.12

Before: 6.1.191

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 2.6.12

Before: 6.6.160

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 2.6.12

Before: 6.12.112

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 2.6.12

Before: 6.18.55

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 2.6.12

Before: 7.2.9

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 2.6.12

Before: 7.3

Applicability preview
[
  {
    "nodes": [
      {
        "operator": "OR",
        "negate": false,
        "cpeMatch": [
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "2.6.12",
            "versionEndExcluding": "5.10.273"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "2.6.12",
            "versionEndExcluding": "5.15.224"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "2.6.12",
            "versionEndExcluding": "6.1.191"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "2.6.12",
            "versionEndExcluding": "6.6.160"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "2.6.12",
            "versionEndExcluding": "6.12.112"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "2.6.12",
            "versionEndExcluding": "6.18.55"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "2.6.12",
            "versionEndExcluding": "7.2.9"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "2.6.12",
            "versionEndExcluding": "7.3"
          }
        ]
      }
    ]
  }
]
Contributing organizations · 1
Linux

Assigning organization

2026-10-30

Timeline

All times UTC

  1. Advisory published

    Publication date supplied by the source.

  2. Source updated

    Latest modification date supplied by the source.

  3. Last imported by cve.new

    Latest catalog import, not the date we first saw this advisory.

What changed

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No substantive changes have been recorded here yet. History starts when cve.new observes a change after tracking is enabled; earlier edits are not reconstructed.

Large field values are marked as truncated previews. Original source snapshots remain retained.