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NVD / CVE Program· CNA Linux

CVE-2026-90036: NFSD: Prevent client use-after-free during blocked-lock reaping

Noroxi assessment

Priority: Monitor (action score 39/100)

  • 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: 0.48% (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 0d53a47c913d0bce3b5ec35c28cbcca4d015f33d, 6fedb2eaff77554ca7a0deffd2e8bc0d6e8b38b0, 7081224a59a0ca4edcd62c068588f4d900199a18; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 0d53a47c913d0bce3b5ec35c28cbcca4d015f33d, 6fedb2eaff77554ca7a0deffd2e8bc0d6e8b38b0, 7081224a59a0ca4edcd62c068588f4d900199a18; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes 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: NFSD: Prevent client use-after-free during blocked-lock reaping A bare lock owner -- its only remaining reference a blocked lock on nn->blocked_locks_lru -- holds a raw pointer to its nfs4_client but no reference keeping the client alive. When the per-net laundromat reaps such a lock, freeing the nbl drops the owner reference held through flc_owner, and the final nfs4_put_stateowner() takes the client's cl_lock. Because the laundromat detaches the nbl first, __destroy_client() no longer finds it, so a concurrent force_expire_client() can free the client before nfs4_put_stateowner() runs, dereferencing cl_lock in freed memory. Pin the client with cl_rpc_users before dropping nn->blocked_locks_lock, and skip clients already expiring, whose blocked locks __destroy_client() frees while holding an owner reference. Take nn->client_lock outside nn->blocked_locks_lock. Every other site holds nn->blocked_locks_lock as a leaf, acquiring no further lock, so placing nn->client_lock outside it cannot form a lock-order cycle.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Sep 16, 2026
Updated
Oct 21, 2026
EPSS
0.4% · 41th percentile
CWE
—

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CNA vs NVD score

NVD
—
CNA · Linux
9.8
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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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

    • 4.9affected
    • 7919d0a27f1e7cb324e023776aa1cbff00f1ee7b and later · before 0d53a47c913d0bce3b5ec35c28cbcca4d015f33daffected · git
    • 7919d0a27f1e7cb324e023776aa1cbff00f1ee7b and later · before 7081224a59a0ca4edcd62c068588f4d900199a18affected · git
    • 7919d0a27f1e7cb324e023776aa1cbff00f1ee7b and later · before cd489b03587378645fe0d20142a33f1ed60bac98affected · git
    • 7919d0a27f1e7cb324e023776aa1cbff00f1ee7b and later · before 6fedb2eaff77554ca7a0deffd2e8bc0d6e8b38b0affected · git
    • 7919d0a27f1e7cb324e023776aa1cbff00f1ee7b and later · before 9026932ac8be4d0ae01db47f23619a98cc57b671affected · git
    • before 4.9not affected · semver
    • 6.6.160 and later · up to and including 6.6.*not affected · semver
    • 6.12.111 and later · up to and including 6.12.*not affected · semver
    • 6.18.51 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
AlmaLinux:10kernelbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.66.1.el10_26.12.0-211.66.1.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-2026-90034Sep 16, 2026 · usb: image: mdc800: change kmalloc() to kzalloc()
    0Monitor
  • ← EarlierCVE-2026-90035Sep 16, 2026 · drm/amd/display: fix division by zero in get_estimated_bw()
    0Monitor
  • Later →CVE-2026-90037Sep 16, 2026 · NFSD: Prevent client use-after-free during close_lru reaping
    39Monitor

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 Linux0d53a47c913d0bce3b5ec35c28cbcca4d015f33dVendor (CNA)
Linux Linux6fedb2eaff77554ca7a0deffd2e8bc0d6e8b38b0Vendor (CNA)
Linux Linux7081224a59a0ca4edcd62c068588f4d900199a18Vendor (CNA)
Linux Linux9026932ac8be4d0ae01db47f23619a98cc57b671Vendor (CNA)
Linux Linuxcd489b03587378645fe0d20142a33f1ed60bac98Vendor (CNA)
azl3 kernel 6.6.150.1-1 on Azure Linux 3.0—Microsoft (MSRC)
azl3 kernel 6.6.152.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
almalinux:bpftool4.18.0-553.174.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel4.18.0-553.174.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel5.14.0-687.58.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k5.14.0-687.58.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-core5.14.0-687.58.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug5.14.0-687.58.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-core5.14.0-687.58.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel5.14.0-687.58.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched5.14.0-687.58.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules5.14.0-687.58.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-core5.14.0-687.58.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra5.14.0-687.58.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel5.14.0-687.58.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel-matched5.14.0-687.58.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-abi-stablelists4.18.0-553.174.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-core4.18.0-553.174.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-cross-headers4.18.0-553.174.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug4.18.0-553.174.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-core4.18.0-553.174.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-devel4.18.0-553.174.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-modules4.18.0-553.174.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-debug-modules-extra4.18.0-553.174.1.el8_10 · AlmaLinux:8Package registry (OSV)

+18

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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

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

Weakness class (CWE)

—

CVSS vector

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

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