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NVD / CVE Program· CNA Linux

CVE-2026-53221: ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()

Noroxi assessment

Priority: Monitor (action score 39/100)

  • 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: 0.57% (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 2abfb19bbb81958714ad1d43ebeb65b30394184b, 2fc7bc087cc7085368263d9d37bfe9a0bddd6a2d, 47fb3c2b4203556308e64354b3e78f2ce221d646; azl3 kernel 6.6.141.1-1 on Azure Linux 3.0 6.6.143.1-1.

Low priority for now. Upgrade to Linux Linux 2abfb19bbb81958714ad1d43ebeb65b30394184b, 2fc7bc087cc7085368263d9d37bfe9a0bddd6a2d, 47fb3c2b4203556308e64354b3e78f2ce221d646; azl3 kernel 6.6.141.1-1 on Azure Linux 3.0 6.6.143.1-1 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: ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup() In vti6_tnl_lookup(), when an exact match for a tunnel fails, the code falls back to searching for wildcard tunnels: - Tunnels matching the packet's local address, with any remote address wildcard remote). - Tunnels matching the packet's remote address, with any local address (wildcard local). However, vti6 stores all these different types of tunnels in the same hash table (ip6n->tnls_r_l) prone to hash collisions. The bug is that the fallback search loops in vti6_tnl_lookup() were missing checks to ensure that the candidate tunnel actually has a wildcard address.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Jun 25, 2026
Updated
Oct 19, 2026
EPSS
0.5% · 47th percentile

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.8
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.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-53221

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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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 kernel3.19 and later · before 5.10.259
  • linux linux kernel5.11 and later · before 5.15.210
  • linux linux kernel5.16 and later · before 6.1.176
  • linux linux kernel6.2 and later · before 6.6.143
  • linux linux kernel6.7 and later · before 6.12.94
  • linux linux kernel6.13 and later · before 6.18.36
  • linux linux kernel6.19 and later · before 7.0.13
  • linux linux kernel7.1

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

    • 3.19affected
    • fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 and later · before c327fa4fca31415431202e063767a7ae342e19c6affected · git
    • fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 and later · before fc657ac0767c49839b3ef0b08dc0953ca30883f8affected · git
    • fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 and later · before 47fb3c2b4203556308e64354b3e78f2ce221d646affected · git
    • fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 and later · before f513f308cc4bdb4530d033431592ffbc29b7fca1affected · git
    • fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 and later · before 90fd4513315ca07da99cfd8549d3e553a7160f0daffected · git
    • fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 and later · before 2abfb19bbb81958714ad1d43ebeb65b30394184baffected · git
    • fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 and later · before 2fc7bc087cc7085368263d9d37bfe9a0bddd6a2daffected · git
    • fbe68ee87522f6eaa10f9076c0a7117e1613f2f7 and later · before a5c0359f5cbc51a2e2b114d6041e0f3c73f903e9affected · git
    • before 3.19not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.176-16.1.176-1
Debian:13linuxbefore 6.12.94-16.12.94-1
Debian:14linuxbefore 7.0.13-17.0.13-1

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-2026-53219Jun 25, 2026 · netfilter: x_tables: avoid leaking percpu counter pointers
    22Monitor
  • ← EarlierCVE-2026-53220Jun 25, 2026 · netfilter: revalidate bridge ports
    22Monitor
  • Later →CVE-2026-53222Jun 25, 2026 · ptp: ocp: fix resource freeing order
    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 Linux2abfb19bbb81958714ad1d43ebeb65b30394184bVendor (CNA)
Linux Linux2fc7bc087cc7085368263d9d37bfe9a0bddd6a2dVendor (CNA)
Linux Linux47fb3c2b4203556308e64354b3e78f2ce221d646Vendor (CNA)
Linux Linux90fd4513315ca07da99cfd8549d3e553a7160f0dVendor (CNA)
Linux Linuxa5c0359f5cbc51a2e2b114d6041e0f3c73f903e9Vendor (CNA)
Linux Linuxc327fa4fca31415431202e063767a7ae342e19c6Vendor (CNA)
Linux Linuxf513f308cc4bdb4530d033431592ffbc29b7fca1Vendor (CNA)
Linux Linuxfc657ac0767c49839b3ef0b08dc0953ca30883f8Vendor (CNA)
azl3 kernel 6.6.141.1-1 on Azure Linux 3.06.6.143.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.176-1 · 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.

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.

  • CVE-2026-6403724 days apartwifi: iwlwifi: mld: fix TSO segmentation explosion when AMSDU is disabled
    39Monitor
  • CVE-2026-6404624 days apartnet: tls: prevent chain-after-chain in plain text SG
    39Monitor
  • CVE-2026-4611528 days apartblock: add pgmap check to biovec_phys_mergeable
    39Monitor
  • CVE-2026-4311450 days apartnetfilter: nft_set_pipapo_avx2: don't return non-matching entry on expiry
    37Monitor
  • CVE-2026-4626622 days apartinet: RAW sockets using IPPROTO_RAW MUST drop incoming ICMP
    36Monitor
  • CVE-2026-6410624 days apartKVM: arm64: vgic-its: Reject restored DTE with out-of-range num_eventid_bits
    36Monitor

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
high · 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
High
Availability impact
High

Weakness class (CWE)

CWE-20 · Improper Input Validation

CVSS vector

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

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