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NVD / CVE Program· CNA Linux

CVE-2026-72254: netfilter: nft_fib: reject fib expression on the netdev egress hook

Noroxi assessment

Priority: Monitor (action score 30/100)

  • 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: 0.66% (FIRST EPSS); higher than 51.8% of all records.
  • 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 1258a6da042c0c283dcf5c581acb318db29c760a, 4fee43759b489559a491f7c95f9bfa7a1d0c7a10, 568931f26af4727a51e8521f72efbc78d3b82410.

Low priority for now. Upgrade to Linux Linux 1258a6da042c0c283dcf5c581acb318db29c760a, 4fee43759b489559a491f7c95f9bfa7a1d0c7a10, 568931f26af4727a51e8521f72efbc78d3b82410 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: nft_fib: reject fib expression on the netdev egress hook A fib expression in a netdev egress base chain dereferences nft_in(pkt), NULL on the transmit path, causing a NULL pointer dereference at eval. nft_fib_validate() masks the hook with NF_INET_* values, but netdev hook numbers are a separate enum that aliases them (NF_NETDEV_EGRESS == NF_INET_LOCAL_IN), so an egress chain passes validation and then faults. Add nft_fib_netdev_validate() that limits each result/flag to the netdev hook where the device it reads exists: the input-device cases (OIF, OIFNAME, ADDRTYPE with F_IIF) to ingress, the output-device case (ADDRTYPE with F_OIF) to egress, ADDRTYPE with no device flag to both. Also restrict nft_fib_validate() to NFPROTO_IPV4/IPV6/INET so its NF_INET_* masks are not applied to another family's hooks.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Aug 15, 2026
Updated
Oct 30, 2026
EPSS
0.6% · 51th percentile
CWE
—

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.6%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.5
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-2026-72254

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.

—

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

    • 5.16affected
    • 42df6e1d221dddc0f2acf2be37e68d553ad65f96 and later · before 1258a6da042c0c283dcf5c581acb318db29c760aaffected · git
    • 42df6e1d221dddc0f2acf2be37e68d553ad65f96 and later · before 4fee43759b489559a491f7c95f9bfa7a1d0c7a10affected · git
    • 42df6e1d221dddc0f2acf2be37e68d553ad65f96 and later · before 568931f26af4727a51e8521f72efbc78d3b82410affected · git
    • 42df6e1d221dddc0f2acf2be37e68d553ad65f96 and later · before d01c913febead04a01a5f3a6374d1f45504dc523affected · git
    • 42df6e1d221dddc0f2acf2be37e68d553ad65f96 and later · before f68305267ebda7e839b5e8f77e8d77535a3d5a0faffected · git
    • 42df6e1d221dddc0f2acf2be37e68d553ad65f96 and later · before d07955dd34ecae17d35d8c7d0a273a3fba653a8caffected · git
    • before 5.16not affected · semver
    • 6.1.191 and later · up to and including 6.1.*not affected · semver
    • 6.6.148 and later · up to and including 6.6.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:12linux-6.12before 6.12.101-1~deb12u16.12.101-1~deb12u1
Debian:13linuxbefore 6.12.101-16.12.101-1
Debian:14linuxbefore 7.1.5-17.1.5-1

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-2026-72252Aug 15, 2026 · netfilter: nft_set_pipapo: don't leak bad clone into future transaction
    31Monitor
  • ← EarlierCVE-2026-72253Aug 15, 2026 · netfilter: nf_conntrack_sip: validate skb_dst() before accessing it
    30Monitor
  • Later →CVE-2026-72255Aug 15, 2026 · netfilter: nf_queue: pin bridge device while NFQUEUE holds fake dst
    31Monitor

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 Linux1258a6da042c0c283dcf5c581acb318db29c760aVendor (CNA)
Linux Linux4fee43759b489559a491f7c95f9bfa7a1d0c7a10Vendor (CNA)
Linux Linux568931f26af4727a51e8521f72efbc78d3b82410Vendor (CNA)
Linux Linuxd01c913febead04a01a5f3a6374d1f45504dc523Vendor (CNA)
Linux Linuxd07955dd34ecae17d35d8c7d0a273a3fba653a8cVendor (CNA)
Linux Linuxf68305267ebda7e839b5e8f77e8d77535a3d5a0fVendor (CNA)
debian:linux6.12.101-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.101-1~deb12u1 · 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.

EPSS, last 120 days

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

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
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

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

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

References

Show all references (5 more)

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

All records