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NVD / CVE Program· CNA Linux

CVE-2026-23083: fou: Don't allow 0 for FOU_ATTR_IPPROTO.

Noroxi assessment

Priority: Monitor (action score 31/100)

  • 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: 0.15% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 1cc98b8887cabb1808d2f4a37cd10a7be7574771, 611ef4bd9c73d9e6d87bed57a635ff1fdd8c91ea, 6e983789b7588ee59cbf303583546c043bad8e19.

Low priority for now. Upgrade to Linux Linux 1cc98b8887cabb1808d2f4a37cd10a7be7574771, 611ef4bd9c73d9e6d87bed57a635ff1fdd8c91ea, 6e983789b7588ee59cbf303583546c043bad8e19 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: fou: Don't allow 0 for FOU_ATTR_IPPROTO. fou_udp_recv() has the same problem mentioned in the previous patch. If FOU_ATTR_IPPROTO is set to 0, skb is not freed by fou_udp_recv() nor "resubmit"-ted in ip_protocol_deliver_rcu(). Let's forbid 0 for FOU_ATTR_IPPROTO.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Feb 4, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 4th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

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-2026-23083

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 kernel3.18 and later · before 5.10.249
  • linux linux kernel5.11 and later · before 5.15.199
  • linux linux kernel5.16 and later · before 6.1.162
  • linux linux kernel6.2 and later · before 6.6.122
  • linux linux kernel6.7 and later · before 6.12.68
  • linux linux kernel6.13 and later · before 6.18.8
  • linux linux kernel6.19

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

    • 3.18affected
    • 23461551c00628c3f3fe9cf837bf53cf8f212b63 and later · before c7498f9bc390479ccfad7c7f2332237ff4945b03affected · git
    • 23461551c00628c3f3fe9cf837bf53cf8f212b63 and later · before 611ef4bd9c73d9e6d87bed57a635ff1fdd8c91eaaffected · git
    • 23461551c00628c3f3fe9cf837bf53cf8f212b63 and later · before 6e983789b7588ee59cbf303583546c043bad8e19affected · git
    • 23461551c00628c3f3fe9cf837bf53cf8f212b63 and later · before 1cc98b8887cabb1808d2f4a37cd10a7be7574771affected · git
    • 23461551c00628c3f3fe9cf837bf53cf8f212b63 and later · before b7db31a52c3862a1a32202a273a4c32e7f5f4823affected · git
    • 23461551c00628c3f3fe9cf837bf53cf8f212b63 and later · before 9b75dff8446ec871030d8daf5a69e74f5fe8b956affected · git
    • 23461551c00628c3f3fe9cf837bf53cf8f212b63 and later · before 7a9bc9e3f42391e4c187e099263cf7a1c4b69ff5affected · git
    • before 3.18not affected · semver
    • 5.10.249 and later · up to and including 5.10.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.162-16.1.162-1
Debian:13linuxbefore 6.12.69-16.12.69-1
Debian:14linuxbefore 6.18.8-16.18.8-1

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-2026-23076Feb 4, 2026 · ALSA: ctxfi: Fix potential OOB access in audio mixer handling
    28Monitor
  • ← EarlierCVE-2026-23078Feb 4, 2026 · ALSA: scarlett2: Fix buffer overflow in config retrieval
    31Monitor
  • Later →CVE-2026-23084Feb 4, 2026 · be2net: Fix NULL pointer dereference in be_cmd_get_mac_from_list
    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 Linux1cc98b8887cabb1808d2f4a37cd10a7be7574771Vendor (CNA)
Linux Linux611ef4bd9c73d9e6d87bed57a635ff1fdd8c91eaVendor (CNA)
Linux Linux6e983789b7588ee59cbf303583546c043bad8e19Vendor (CNA)
Linux Linux7a9bc9e3f42391e4c187e099263cf7a1c4b69ff5Vendor (CNA)
Linux Linux9b75dff8446ec871030d8daf5a69e74f5fe8b956Vendor (CNA)
Linux Linuxb7db31a52c3862a1a32202a273a4c32e7f5f4823Vendor (CNA)
Linux Linuxc7498f9bc390479ccfad7c7f2332237ff4945b03Vendor (CNA)
debian:linux6.1.162-1 · 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-2026-46115113 days apartblock: add pgmap check to biovec_phys_mergeable
    39Monitor
  • CVE-2026-53221141 days apartip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()
    39Monitor
  • CVE-2026-64037165 days apartwifi: iwlwifi: mld: fix TSO segmentation explosion when AMSDU is disabled
    39Monitor
  • CVE-2026-64046165 days apartnet: tls: prevent chain-after-chain in plain text SG
    39Monitor
  • CVE-2026-4311491 days apartnetfilter: nft_set_pipapo_avx2: don't return non-matching entry on expiry
    37Monitor
  • CVE-2026-46266119 days apartinet: RAW sockets using IPPROTO_RAW MUST drop incoming ICMP
    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

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • 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
Local
Attack complexity
Low
Privileges required
Low
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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-primary

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. 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