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CVE-2026-89712· NVD / CVE Program· CNA Linux

NFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock

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: 0.71% (FIRST EPSS); higher than 52.7% 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.
  • Fixed version: Linux Linux 036c1b182f4da65363e79ec0ac276edc6b7296e5, 2b59029b8f24a99b5d844af2da3950d39d36eeea, 4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 036c1b182f4da65363e79ec0ac276edc6b7296e5, 2b59029b8f24a99b5d844af2da3950d39d36eeea, 4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8 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: restart ssc_expire_umount walk after dropping nfsd_ssc_lock nfsd4_ssc_expire_umount() walks nn->nfsd_ssc_mount_list with list_for_each_entry_safe(ni, tmp, ...). For each expired entry it sets nsui_busy = true, drops nfsd_ssc_lock to run mntput() on the source vfsmount, then reacquires the lock to list_del + kfree the entry and continue iterating via the macro's saved tmp pointer. The nsui_busy flag protects the current ni from concurrent nfsd4_ssc_setup_dul() finders during the lock-drop window, but it does not pin tmp. Another nfsd RPC thread that fails its source- server mount and reaches nfsd4_ssc_cancel_dul() will, during that same window, take nfsd_ssc_lock, list_del + kfree its own ssc_umount item, and release the lock. If that item is the saved tmp of the expire walk, the next iteration dereferences a freed nfsd4_ssc_umount_item. Restart the walk from the head after the mntput() unlock window so no saved next pointer survives the lock-drop. The list is bounded by the number of active inter-server source mounts (typically small) and the expire delayed-work runs periodically rather than per-IO, so the restart is cheap.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Sep 11, 2026
Updated
Sep 14, 2026
EPSS
0.7% · 52th 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 · 0.7%

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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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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When you'll hear from us

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  • when exploit code appears or is weaponized
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  • 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

    • 5.14affected
    • a4bc287943f5695209ff36bdc89f17b48d68fae7 and later · before 2b59029b8f24a99b5d844af2da3950d39d36eeeaaffected · git
    • f4e44b393389c77958f7c58bf4415032b4cda15b and later · before d9e151fea5ed706c1284adacabd869b0be745db2affected · git
    • f4e44b393389c77958f7c58bf4415032b4cda15b and later · before 659ee3da073164e1e6e40dfcbc26eeed85845f93affected · git
    • f4e44b393389c77958f7c58bf4415032b4cda15b and later · before 60680ae7243b22de3d09be990d8e23bcfc4af837affected · git
    • f4e44b393389c77958f7c58bf4415032b4cda15b and later · before 77de363d9a1c8cd35f20482782c612cda085791aaffected · git
    • f4e44b393389c77958f7c58bf4415032b4cda15b and later · before 4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8affected · git
    • f4e44b393389c77958f7c58bf4415032b4cda15b and later · before 7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9affected · git
    • f4e44b393389c77958f7c58bf4415032b4cda15b and later · before 036c1b182f4da65363e79ec0ac276edc6b7296e5affected · git
    • 5.10.220 and later · before 5.10.270affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxall versions—
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

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    40Plan
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  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
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  • CVE-2026-74279crypto: cavium/cpt - fix DMA cleanup using wrong loop index
    40Plan
  • CVE-2026-72421ipv4: fib: Don't ignore error route in local/main tables.
    40Plan
  • CVE-2026-74309vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
    40Plan

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 Linux036c1b182f4da65363e79ec0ac276edc6b7296e5Vendor (CNA)
Linux Linux2b59029b8f24a99b5d844af2da3950d39d36eeeaVendor (CNA)
Linux Linux4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8Vendor (CNA)
Linux Linux5.10.270Vendor (CNA)
Linux Linux60680ae7243b22de3d09be990d8e23bcfc4af837Vendor (CNA)
Linux Linux659ee3da073164e1e6e40dfcbc26eeed85845f93Vendor (CNA)
Linux Linux7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9Vendor (CNA)
Linux Linux77de363d9a1c8cd35f20482782c612cda085791aVendor (CNA)
Linux Linuxd9e151fea5ed706c1284adacabd869b0be745db2Vendor (CNA)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~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+1% in 7 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 (7 more)

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

All records