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NVD / CVE Program· CNA Linux

CVE-2026-89663: nfsd: revoke copy-notify stateids before dropping their reference

Noroxi assessment

Priority: Monitor (action score 35/100)

  • 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: 0.45% (FIRST EPSS).
  • Anyone who can reach it over the internet 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 06a62f6dbc60791f4229c6950b1eec6b18df9af1, 3b0c3595db99bb4bebd7c8aa8a36f3c50e411bb7, 5f00e0ab4de45d4f9e4bd0883cf2517acf63fc0d.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 06a62f6dbc60791f4229c6950b1eec6b18df9af1, 3b0c3595db99bb4bebd7c8aa8a36f3c50e411bb7, 5f00e0ab4de45d4f9e4bd0883cf2517acf63fc0d 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: revoke copy-notify stateids before dropping their reference Copy-notify stateids live in the s2s_cp_stateids IDR and on their parent stid's sc_cp_list, pinned by a single membership reference. _free_cpntf_state_locked() only unlinks an entry once its refcount reaches zero, so any revoke path that runs while a concurrent find_cpntf_state()/manage_cpntf_state() holder has elevated cs_count drops the reference without unlinking, leaving the entry discoverable with its membership reference already consumed. A second revoke or a laundromat tick then frees it while the reader still holds the pointer -- a KASAN-detectable use-after-free at the reader's nfs4_put_cpntf_state(). This affected all three revoke paths: - The parent-stid drain (nfs4_free_cpntf_statelist()) repeatedly called _free_cpntf_state_locked() on the first list entry; a holder that had bumped cs_count made it return early, so the next iteration re-decremented and burned the holder's reference. - OFFLOAD_CANCEL (manage_cpntf_state()) and laundromat expiry likewise used _free_cpntf_state_locked() and could drop 2->1 without unlinking. Add revoke_cpntf_state_locked(), which unhashes the entry from the IDR and sc_cp_list first (deferring the final free to any holder), and use it from all three revoke paths. The drain now walks with list_for_each_entry_safe() and revokes each entry unconditionally, so it terminates in one pass per entry regardless of cs_count. The unhash is gated on !list_empty(&cps->cp_list); the idr_remove() gate matters because idr_alloc_cyclic() may have recycled the so_id by then. Keep _free_cpntf_state_locked() for the reference-holder put path only, where a concurrent revoke may already have unlinked the entry (its list_del_init() then a no-op).

HighCVSS 8.8 · v3.1—No exploit Fix available
Published
Sep 11, 2026
Updated
Oct 19, 2026
EPSS
0.4% · 39th percentile
CWE
—

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CNA vs NVD score

NVD
—
CNA · Linux
8.8
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

    • 5.6affected
    • 624322f1adc58acd0b69f77a6ddc764207e97241 and later · before 5f00e0ab4de45d4f9e4bd0883cf2517acf63fc0daffected · git
    • 624322f1adc58acd0b69f77a6ddc764207e97241 and later · before 06a62f6dbc60791f4229c6950b1eec6b18df9af1affected · git
    • 624322f1adc58acd0b69f77a6ddc764207e97241 and later · before a1fca0f7bbb7b100a39c7ba8dd7922c87c4237a3affected · git
    • 624322f1adc58acd0b69f77a6ddc764207e97241 and later · before caddbeffab1eaba1d2bcf5ceda35547863466705affected · git
    • 624322f1adc58acd0b69f77a6ddc764207e97241 and later · before 6b8149448cdcb476fba4559d1ecc247efee9971baffected · git
    • 624322f1adc58acd0b69f77a6ddc764207e97241 and later · before b56d2c5f01cddbeca7d11cce81d97db4ec9a464faffected · git
    • 624322f1adc58acd0b69f77a6ddc764207e97241 and later · before ff8a3cff02b92b2a82f1a9876038fcf953ae9c25affected · git
    • 624322f1adc58acd0b69f77a6ddc764207e97241 and later · before 3b0c3595db99bb4bebd7c8aa8a36f3c50e411bb7affected · git
    • before 5.6not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.64.1.el10_26.12.0-211.64.1.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-2026-89661Sep 11, 2026 · NFSD: Prevent post-shutdown use-after-free in unlock_filesystem
    0Monitor
  • ← EarlierCVE-2026-89662Sep 11, 2026 · NFSD: Prevent lock owner use-after-free during client teardown
    39Monitor
  • Later →CVE-2026-89664Sep 11, 2026 · nfsd: release OPEN-decoded posix ACLs via op_release
    30Monitor

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 Linux06a62f6dbc60791f4229c6950b1eec6b18df9af1Vendor (CNA)
Linux Linux3b0c3595db99bb4bebd7c8aa8a36f3c50e411bb7Vendor (CNA)
Linux Linux5f00e0ab4de45d4f9e4bd0883cf2517acf63fc0dVendor (CNA)
Linux Linux6b8149448cdcb476fba4559d1ecc247efee9971bVendor (CNA)
Linux Linuxa1fca0f7bbb7b100a39c7ba8dd7922c87c4237a3Vendor (CNA)
Linux Linuxb56d2c5f01cddbeca7d11cce81d97db4ec9a464fVendor (CNA)
Linux Linuxcaddbeffab1eaba1d2bcf5ceda35547863466705Vendor (CNA)
Linux Linuxff8a3cff02b92b2a82f1a9876038fcf953ae9c25Vendor (CNA)
almalinux:kernel5.14.0-687.56.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel6.12.0-211.64.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k5.14.0-687.56.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k6.12.0-211.64.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-core5.14.0-687.56.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-core6.12.0-211.64.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug5.14.0-687.56.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug6.12.0-211.64.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-core5.14.0-687.56.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-core6.12.0-211.64.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel5.14.0-687.56.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel6.12.0-211.64.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched5.14.0-687.56.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched6.12.0-211.64.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules5.14.0-687.56.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules6.12.0-211.64.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-core5.14.0-687.56.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-core6.12.0-211.64.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra5.14.0-687.56.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra6.12.0-211.64.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel5.14.0-687.56.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel6.12.0-211.64.1.el10_2 · AlmaLinux:10Package 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.
  • 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
Network
Attack complexity
Low
Privileges required
Low
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:L/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 (7 more)

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

All records