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NVD / CVE Program· CNA Linux

CVE-2026-31685: netfilter: ip6t_eui64: reject invalid MAC header for all packets

Noroxi assessment

Priority: Monitor (action score 37/100)

  • 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: 0.48% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 288138418bef956f8b295751a4536c60f0e89f4a, 309ae3e9a51a69699ca94eac5fac5688fa562d55, 4d75bc2cd093bf5803edf512c099bfb220fd6459; azl3 kernel 6.6.134.1-2 on Azure Linux 3.0 6.6.137.1-1.

Low priority for now. Upgrade to Linux Linux 288138418bef956f8b295751a4536c60f0e89f4a, 309ae3e9a51a69699ca94eac5fac5688fa562d55, 4d75bc2cd093bf5803edf512c099bfb220fd6459; azl3 kernel 6.6.134.1-2 on Azure Linux 3.0 6.6.137.1-1 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: netfilter: ip6t_eui64: reject invalid MAC header for all packets `eui64_mt6()` derives a modified EUI-64 from the Ethernet source address and compares it with the low 64 bits of the IPv6 source address. The existing guard only rejects an invalid MAC header when `par->fragoff != 0`. For packets with `par->fragoff == 0`, `eui64_mt6()` can still reach `eth_hdr(skb)` even when the MAC header is not valid. Fix this by removing the `par->fragoff != 0` condition so that packets with an invalid MAC header are rejected before accessing `eth_hdr(skb)`.

CriticalCVSS 9.4 · v3.1—No exploit Fix available
Published
Apr 25, 2026
Updated
Oct 19, 2026
EPSS
0.4% · 42th percentile

Report tools

JSON

Action score

37

Monitor

Low priority for now.

CVSS
37 / 40 · 9.4 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.4
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • Not in KEV: no record of exploitation in the wild
  • 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.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel2.6.12.1 and later · before 6.6.136
  • linux linux kernel6.7 and later · before 6.12.83
  • linux linux kernel6.13 and later · before 6.18.24
  • linux linux kernel6.19 and later · before 6.19.14
  • linux linux kernel2.6.12
  • linux linux kernel7.0

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 4d75bc2cd093bf5803edf512c099bfb220fd6459affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 7d6a57411caf54df025860c9b1a82cd42d57a562affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before d5603591373441fecf9951833d6d873e09320f08affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 288138418bef956f8b295751a4536c60f0e89f4aaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 9eda5478746ef7dc0e4e537b5a5e4b0ca1027091affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 807d6ee15804df6f01a35c910f09612e858739a6affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 309ae3e9a51a69699ca94eac5fac5688fa562d55affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before fdce0b3590f724540795b874b4c8850c90e6b0a8affected · 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
AlmaLinux:10kernelbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.18.1.el10_26.12.0-211.18.1.el10_2

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe…KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-31682Apr 25, 2026 · bridge: br_nd_send: linearize skb before parsing ND options
    36Monitor
  • ← EarlierCVE-2026-31684Apr 25, 2026 · net: sched: act_csum: validate nested VLAN headers
    22Monitor
  • Later →CVE-2026-31687Apr 27, 2026 · gpio: omap: do not register driver in probe()
    22Monitor

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 Linux288138418bef956f8b295751a4536c60f0e89f4aVendor (CNA)
Linux Linux309ae3e9a51a69699ca94eac5fac5688fa562d55Vendor (CNA)
Linux Linux4d75bc2cd093bf5803edf512c099bfb220fd6459Vendor (CNA)
Linux Linux7d6a57411caf54df025860c9b1a82cd42d57a562Vendor (CNA)
Linux Linux807d6ee15804df6f01a35c910f09612e858739a6Vendor (CNA)
Linux Linux9eda5478746ef7dc0e4e537b5a5e4b0ca1027091Vendor (CNA)
Linux Linuxd5603591373441fecf9951833d6d873e09320f08Vendor (CNA)
Linux Linuxfdce0b3590f724540795b874b4c8850c90e6b0a8Vendor (CNA)
azl3 kernel 6.6.134.1-2 on Azure Linux 3.06.6.137.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:kernel5.14.0-687.12.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k5.14.0-687.12.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-core5.14.0-687.12.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug5.14.0-687.12.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-core5.14.0-687.12.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel5.14.0-687.12.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched5.14.0-687.12.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules5.14.0-687.12.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-core5.14.0-687.12.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra5.14.0-687.12.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel5.14.0-687.12.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel-matched5.14.0-687.12.1.el9_8 · AlmaLinux:9Package registry (OSV)
debian:linux6.1.176-1 · Debian:12Package registry (OSV)
red hat:kernel-64k-debug-debuginfo0:5.14.0-687.12.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel0:5.14.0-687.12.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel-matched0:5.14.0-687.12.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debuginfo0:5.14.0-687.12.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-devel0:5.14.0-687.12.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-devel-matched0:5.14.0-687.12.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debug-debuginfo0:5.14.0-687.12.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debug-devel0:5.14.0-687.12.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)

+18

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.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

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).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
low · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
Low
Availability impact
High

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H

nvd-secondary

Attack context

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

ATT&CK techniques

—

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

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

References

Show all references (8 more)

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

All records