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

CVE-2026-99999: ipv4: validate checksum_start before completing checksum

CriticalCVSS 9.3 · v3.1—Proof of concept Fix available

Noroxi assessment

Priority: Monitor (action score 37/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.78% (FIRST EPSS); higher than 56.6% of all records.
  • Someone with local access to the system can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 0fab003ef4698e0628060a45a48f14b43ba2a40a, 32a8b0adaa18e52aaa0b246b5ffe683075354dbb, 6785011f8b16abf40b1e9d8b2e332232b3e68822; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.159.1-1.

Low priority for now. Upgrade to Linux Linux 0fab003ef4698e0628060a45a48f14b43ba2a40a, 32a8b0adaa18e52aaa0b246b5ffe683075354dbb, 6785011f8b16abf40b1e9d8b2e332232b3e68822; 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: ipv4: validate checksum_start before completing checksum If a packet with bad checksum metadata gets into the ipv4 stack, skb_checksum_help can corrupt the network header and cause a bunch of mischief. This was discovered and reported by Paulos, and has been reporoduced by others independently since. We really shouldn't allow such packets in, but as a defence in depth measure, let's also check before we complete the checksum. A more complete validation at input is forthcoming, but needs more work.

Published
Oct 15, 2026
Updated
Oct 24, 2026
EPSS
0.7% · 56th percentile

Report tools

JSON

Action score

37

Monitor

Low priority for now.

CVSS
37 / 40 · 9.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.7%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.3
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
  • Proof of concept exists, no weaponized module
  • A fix has been released

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

Follow CVE-2026-99999

When you'll hear from us

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  • 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.

—

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

    • 2.6.27affected
    • f43798c27684ab925adde7d8acc34c78c6e50df8 and later · before a464d950f31c89565cbaae038cc60db04fe01956affected · git
    • f43798c27684ab925adde7d8acc34c78c6e50df8 and later · before 0fab003ef4698e0628060a45a48f14b43ba2a40aaffected · git
    • f43798c27684ab925adde7d8acc34c78c6e50df8 and later · before 94524b7b32691de2e2ce162c04d6cbc9106e5cbfaffected · git
    • f43798c27684ab925adde7d8acc34c78c6e50df8 and later · before a65f69e0f38ffbed1b128029e09097436416dc8baffected · git
    • f43798c27684ab925adde7d8acc34c78c6e50df8 and later · before 32a8b0adaa18e52aaa0b246b5ffe683075354dbbaffected · git
    • f43798c27684ab925adde7d8acc34c78c6e50df8 and later · before f3e835af6226f1dd12160cbd696081e9b6155de0affected · git
    • f43798c27684ab925adde7d8acc34c78c6e50df8 and later · before c3e33464746166264334641dc850a36eef7e6326affected · git
    • f43798c27684ab925adde7d8acc34c78c6e50df8 and later · before 6785011f8b16abf40b1e9d8b2e332232b3e68822affected · git
    • before 2.6.27not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.67.1.el10_26.12.0-211.67.1.el10_2

+96

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-2026-98430Oct 14, 2026 · RDMA/efa: Keep admin queues alive while IRQ is registered
    0Monitor
  • ← EarlierCVE-2026-98431Oct 14, 2026 · RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency
    0Monitor
  • Later →CVE-2026-98433Oct 18, 2026 · KVM: PPC: Book3S HV: fix secure device page leak on uv_page_in() failure
    0Monitor

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 Linux0fab003ef4698e0628060a45a48f14b43ba2a40aVendor (CNA)
Linux Linux32a8b0adaa18e52aaa0b246b5ffe683075354dbbVendor (CNA)
Linux Linux6785011f8b16abf40b1e9d8b2e332232b3e68822Vendor (CNA)
Linux Linux94524b7b32691de2e2ce162c04d6cbc9106e5cbfVendor (CNA)
Linux Linuxa464d950f31c89565cbaae038cc60db04fe01956Vendor (CNA)
Linux Linuxa65f69e0f38ffbed1b128029e09097436416dc8bVendor (CNA)
Linux Linuxc3e33464746166264334641dc850a36eef7e6326Vendor (CNA)
Linux Linuxf3e835af6226f1dd12160cbd696081e9b6155de0Vendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.06.6.159.1-1 · Release NotesMicrosoft (MSRC)
almalinux:kernel5.14.0-687.59.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel6.12.0-211.67.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k5.14.0-687.59.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k6.12.0-211.67.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-core5.14.0-687.59.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-core6.12.0-211.67.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug5.14.0-687.59.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug6.12.0-211.67.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-core5.14.0-687.59.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-core6.12.0-211.67.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel5.14.0-687.59.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel6.12.0-211.67.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched5.14.0-687.59.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched6.12.0-211.67.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules5.14.0-687.59.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules6.12.0-211.67.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-core5.14.0-687.59.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-core6.12.0-211.67.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra5.14.0-687.59.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra6.12.0-211.67.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel5.14.0-687.59.1.el9_8 · AlmaLinux:9Package registry (OSV)

+15

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×14

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHub14 repositories2026-10-16 → 2026-10-25

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. First PoCsame day
  4. TodayNov 13, 2026+29 d
EPSS, last 120 days+1% in 7 days

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

Variant candidates

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

  • CVE-2026-6847761 days apartipvs: fix more places with wrong ipv6 transport offsets
    39Monitor
  • CVE-2026-7206561 days apartnet: mana: Validate the packet length reported by the NIC
    39Monitor
  • CVE-2026-6815466 days apartlibceph: reject zero bucket types in crush_decode
    39Monitor
  • CVE-2026-6847061 days apartwifi: mac80211: validate extension-frame layout before RX
    35Monitor
  • CVE-2026-6845463 days apartKVM: s390: pci: Fix handling of AIF enable without AISB
    35Monitor
  • CVE-2026-6819966 days apartwifi: ath6kl: fix OOB access from firmware ADDBA window size
    35Monitor

Not on record for this CVE: patch commit or PR link · researcher credit · public bounty program.

Technical details

Attack conditions

  • Someone with local access to the system 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

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-20 · Improper Input Validation

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/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. Exploit maturitynone → poc
  2. SSVC exploitation— → none
  3. Exploit maturity— → none
  4. Fix✗ → ✓

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

References

Show all references (10 more)

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

All records