Investigate in your agent.

Turn this advisory into a focused investigation. Ask your agent to check your project’s versions, explain the evidence, and suggest a compatible fix.

Your agent needs remote MCP support and access to https://cve.new/mcp.

Read the setup guide

Skip to content
cve.newCreate a CVE report
Check your stack
CVE-2026-99041

ip6_gre: remove obsolete ERSPAN PMTU update

Products / packages Linux

Published

Share

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

Source guidance available

Review the recorded instructions. Guidance may be a workaround rather than a fixed version.

What this means

The Linux kernel has a vulnerability in ip6_gre where a null pointer dereference can occur, potentially causing a kernel panic. This issue affects Linux kernel versions starting from 4.16. An attacker with access to a vulnerable system may be able to trigger this issue. The vulnerability is due to an obsolete ERSPAN PMTU update.

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

Attack conditions

No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.

Review supporting sources →

Affected versions

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

Linux · Linux

Linux

7 ranges
Linux version evidence

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

affected

5a963eb61b7c39e6c422b6e48619d19d04719358 → before 2e151c74bcc53e3ed313bd1c21b0d5bb442edbc0

git versions

5a963eb61b7c39e6c422b6e48619d19d04719358 → before ba72ed1c8476ce68eb7152dfcbc5330cefcbaa91

git versions

5a963eb61b7c39e6c422b6e48619d19d04719358 → before b14a682ad7d45345701e08f9279d483a1da8b36c

git versions

5a963eb61b7c39e6c422b6e48619d19d04719358 → before f5b143f4cd3fb7673df8d727550478a4b762908a

git versions

5a963eb61b7c39e6c422b6e48619d19d04719358 → before 2d06cb25a497d3a7034ef9d172626c2d6620a0f1

git versions

5a963eb61b7c39e6c422b6e48619d19d04719358 → before 8f27260b989f488760289276377db24fbfb20bfa

git versions

5a963eb61b7c39e6c422b6e48619d19d04719358 → before 8bc60db48e8cba35488bbd6e1f94aa990afa275a

git versions

unaffected

unknown

Other versions: unaffected

Linux · Linux

Linux

9 ranges
Linux version evidence

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

affected

4.16

unaffected

0 → before 4.16

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

6.12.114 → through 6.12.*

semver versions

6.18.58 → through 6.18.*

semver versions

7.2.11 → 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.

Remove the stale ERSPAN copy and its now-unused dst variable.

Linux guidance ↗

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:

ip6_gre: remove obsolete ERSPAN PMTU update

A tc tunnel_key action can attach a METADATA_IP_TUNNEL dst to an skb, and mirred can redirect it to a native ip6erspan device. The legacy PMTU update in ip6erspan_tunnel_xmit() treats that metadata dst as a route. Since it has no output device, dst_dev(dst)->mtu dereferences NULL.

On v7.2 with KASAN, an initial UID/GID 65534 process with CapEff 0 used self-created user and network namespaces to trigger:

KASAN: null-ptr-deref RIP: ip6erspan_tunnel_xmit+0x10fc/0x2cc0 Kernel panic - not syncing: Fatal exception in interrupt

The update is obsolete. Commit fe1a4ca0a2b7 ("ip6_gre: process toobig in a better way") changed IPv6 GRE Too Big handling to update the underlay route and removed the equivalent block from __gre6_xmit(). ip6_tnl_xmit() then propagates the underlay PMTU to the overlay route.

Remove the stale ERSPAN copy and its now-unused dst variable. This eliminates the metadata-dst dereference and keeps ERSPAN aligned with IPv6 GRE PMTU handling.

References

7 sources
git.kernel.org/stable/c/2e151c74bcc53e3ed313bd1c21b0d5bb442edbc0
Source referenceLinux
git.kernel.org/stable/c/ba72ed1c8476ce68eb7152dfcbc5330cefcbaa91
Source referenceLinux
git.kernel.org/stable/c/b14a682ad7d45345701e08f9279d483a1da8b36c
Source referenceLinux
git.kernel.org/stable/c/f5b143f4cd3fb7673df8d727550478a4b762908a
Source referenceLinux
git.kernel.org/stable/c/2d06cb25a497d3a7034ef9d172626c2d6620a0f1
Source referenceLinux
git.kernel.org/stable/c/8f27260b989f488760289276377db24fbfb20bfa
Source referenceLinux
View 1 more references
git.kernel.org/stable/c/8bc60db48e8cba35488bbd6e1f94aa990afa275a
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-2026-99041

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): 4.16

Before: 5.15.224

Vulnerable product

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

From (inclusive): 4.16

Before: 6.1.191

Vulnerable product

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

From (inclusive): 4.16

Before: 6.6.160

Vulnerable product

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

From (inclusive): 4.16

Before: 6.12.114

Vulnerable product

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

From (inclusive): 4.16

Before: 6.18.58

Vulnerable product

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

From (inclusive): 4.16

Before: 7.2.11

Vulnerable product

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

From (inclusive): 4.16

Before: 7.3

Applicability preview
[
  {
    "nodes": [
      {
        "operator": "OR",
        "negate": false,
        "cpeMatch": [
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "4.16",
            "versionEndExcluding": "5.15.224"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "4.16",
            "versionEndExcluding": "6.1.191"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "4.16",
            "versionEndExcluding": "6.6.160"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "4.16",
            "versionEndExcluding": "6.12.114"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "4.16",
            "versionEndExcluding": "6.18.58"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "4.16",
            "versionEndExcluding": "7.2.11"
          },
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "4.16",
            "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

Follow changes
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.