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NVD / CVE Program· CNA Linux

CVE-2026-90149: NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers

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: 0.61% (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.
  • Fixed version: Linux Linux 163c16e01f53fc8eb8d0f3484ae6c382265ecbbd, 2b03ebbf8d5e8f6af4ecd6c65375232dd1ec32cc, 336b6da10021c69a8f273bbacdf7432fdc89a06f.

Low priority for now. Upgrade to Linux Linux 163c16e01f53fc8eb8d0f3484ae6c382265ecbbd, 2b03ebbf8d5e8f6af4ecd6c65375232dd1ec32cc, 336b6da10021c69a8f273bbacdf7432fdc89a06f 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: NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers flexfiles accepts NFSv4.0 data servers, but two NFSv4 code paths assume the data server client has a session. Unlike NFSv4.1+, an NFSv4.0 client has no session (clp->cl_session is NULL; it uses clp->cl_slot_tbl), so I/O to a v4.0 flexfiles DS oopses: - nfs4_init_ds_session() dereferences clp->cl_session->session_state while seeding the DS lease. It also only seeds cl_lease_time when NFS4_SESSION_INITING is set; without a session that never happens, so cl_lease_time stays 0 and nfs4_renew_state() busy-loops, requeuing every 5 seconds. Seed the lease whenever there is no session and return before touching session state. - ff_layout_async_handle_error_v4() dereferences clp->cl_session->fc_slot_table on every DS I/O error. Fall back to the v4.0 transport slot table (clp->cl_slot_tbl) when there is no session.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Sep 17, 2026
Updated
Oct 21, 2026
EPSS
0.6% · 48th 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%

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-2026-90149

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

    • 4.12affected
    • a7878ca140084ec267ede48fce64d7e60f6d873e and later · before 336b6da10021c69a8f273bbacdf7432fdc89a06faffected · git
    • a7878ca140084ec267ede48fce64d7e60f6d873e and later · before 5527af72b0100c94287bfec901b6313eeac567caaffected · git
    • a7878ca140084ec267ede48fce64d7e60f6d873e and later · before 163c16e01f53fc8eb8d0f3484ae6c382265ecbbdaffected · git
    • a7878ca140084ec267ede48fce64d7e60f6d873e and later · before 436a214514e24103159aea455147d58b44a8a585affected · git
    • a7878ca140084ec267ede48fce64d7e60f6d873e and later · before 2b03ebbf8d5e8f6af4ecd6c65375232dd1ec32ccaffected · git
    • before 4.12not affected · semver
    • 6.6.160 and later · up to and including 6.6.*not affected · semver
    • 6.12.114 and later · up to and including 6.12.*not affected · semver
    • 6.18.52 and later · up to and including 6.18.*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:14linuxbefore 7.2.6-17.2.6-1
openSUSE:Tumbleweedkernel-sourcebefore 7.2.8-1.17.2.8-1.1

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-2026-90147Sep 17, 2026 · clk: devres: fix cleanup in devm_clk_get_optional_enabled_with_rate()
    0Monitor
  • ← EarlierCVE-2026-90148Sep 17, 2026 · NFSv4: Fix incorrect argument passed to nfs4_delete_lease() in nfs4_add_lease()
    0Monitor
  • Later →CVE-2026-90150Sep 17, 2026 · pnfs/blocklayout: Fix device leaks on parse 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 Linux163c16e01f53fc8eb8d0f3484ae6c382265ecbbdVendor (CNA)
Linux Linux2b03ebbf8d5e8f6af4ecd6c65375232dd1ec32ccVendor (CNA)
Linux Linux336b6da10021c69a8f273bbacdf7432fdc89a06fVendor (CNA)
Linux Linux436a214514e24103159aea455147d58b44a8a585Vendor (CNA)
Linux Linux5527af72b0100c94287bfec901b6313eeac567caVendor (CNA)
debian:linux7.2.6-1 · Debian:14Package registry (OSV)
opensuse:kernel-source7.2.8-1.1 · openSUSE:TumbleweedPackage 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. Fix✗ → ✓

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

References

Show all references (4 more)

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

All records