CVE-2026-90149High· 7.5▾ Twilight

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 ses…

▾ Twilight zone — High severity, or a signal on a lesser flaw

Depth score41/ 100 · Moderate

impact 41.3 · likelihood 0.1 · exploitation 0

⚡ Agent-ready:Raw markdown ↗JSON ↗

Proof of concept

Need a working PoC? Pro members can cast a request and our team develops one — it lands right here.

…

Published

Sep 17, 2026

Updated

Sep 18, 2026

CVSS

7.5

Vendor

Linux

Product

Linux

CWE

—

Depth score

41 · Moderate

EPSS

0.61% · p49

Platforms

—

Source

NVD

Vector

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

EPSS history

Exploit-prediction probability, daily snapshots since Sep 18.

0.2% → 0.6%▲ 0.4%

Timeline

Disclosure to exploitation, from the record and what we observed since indexing it.

6 events · 36 days

Sep 17, 2026Published
Disclosed via NVD
Sep 18, 2026Record revised
Last analysed / modified upstream
Sep 18, 2026EPSS first tracked
0.2%
Sep 18, 2026CVSS changed
— → 7.5
Sep 18, 2026Severity changed
none → high
Oct 23, 2026EPSS peak
0.2% → 0.6%

Linux #nvd #cve.org

Affected

Linux >= a7878ca140084ec267ede48fce64d7e60f6d873e < 163c16e01f53fc8eb8d0f3484ae6c382265ecbbd
Linux >= a7878ca140084ec267ede48fce64d7e60f6d873e < 436a214514e24103159aea455147d58b44a8a585
Linux >= a7878ca140084ec267ede48fce64d7e60f6d873e < 2b03ebbf8d5e8f6af4ecd6c65375232dd1ec32cc
Linux 4.12

Full technical detail▾

Overview

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.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

References

Change history

Field changes observed since this record was first indexed.

Sep 18, 2026CVSS — → 7.5
Sep 18, 2026Severity none → high

Related vulnerabilities

Connected by shared product, vendor, weakness, or advisory.

#nvd#cve.org

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CVE-2026-90149High· 7.5▾ Twilight

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 ses…

▾ Twilight zone — High severity, or a signal on a lesser flaw

Depth score41/ 100 · Moderate

impact 41.3 · likelihood 0.1 · exploitation 0

⚡ Agent-ready:Raw markdown ↗JSON ↗

Proof of concept

Need a working PoC? Pro members can cast a request and our team develops one — it lands right here.

…

Published

Sep 17, 2026

Updated

Sep 18, 2026

CVSS

7.5

Vendor

Linux

Product

Linux

CWE

—

Depth score

41 · Moderate

EPSS

0.61% · p49

Platforms

—

Source

NVD

Vector

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

EPSS history

Exploit-prediction probability, daily snapshots since Sep 18.

0.2% → 0.6%▲ 0.4%

Timeline

Disclosure to exploitation, from the record and what we observed since indexing it.

6 events · 36 days

Sep 17, 2026Published
Disclosed via NVD
Sep 18, 2026Record revised
Last analysed / modified upstream
Sep 18, 2026EPSS first tracked
0.2%
Sep 18, 2026CVSS changed
— → 7.5
Sep 18, 2026Severity changed
none → high
Oct 23, 2026EPSS peak
0.2% → 0.6%

Linux #nvd #cve.org

Affected

Linux >= a7878ca140084ec267ede48fce64d7e60f6d873e < 163c16e01f53fc8eb8d0f3484ae6c382265ecbbd
Linux >= a7878ca140084ec267ede48fce64d7e60f6d873e < 436a214514e24103159aea455147d58b44a8a585
Linux >= a7878ca140084ec267ede48fce64d7e60f6d873e < 2b03ebbf8d5e8f6af4ecd6c65375232dd1ec32cc
Linux 4.12

Full technical detail▾

Overview

In the Linux kernel, the following vulnerability has been resolved:

NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers

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.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

References

Change history

Field changes observed since this record was first indexed.

Sep 18, 2026CVSS — → 7.5
Sep 18, 2026Severity none → high

Related vulnerabilities

Connected by shared product, vendor, weakness, or advisory.

#nvd#cve.org