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Response snapshot Oct 30, 2026, 19:11 UTC

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VulnerabilityCVE-2026-89707

Linux kernel: nfsd: release path refs on follow_down() error

In the Linux kernel, the following vulnerability has been resolved: nfsd: release path refs on follow_down() error nfsd_cross_mnt() initializes a local struct path with mntget() and dget() before calling follow_down().

At a glance

Exploited
Not known
Severity
7.5 High (CVSS 3.1)
Chance of exploitation
0.6% in the next 30 days
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-89707 (opens a new tab)

What happened

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

nfsd: release path refs on follow_down() error

nfsd_cross_mnt() initializes a local struct path with mntget() and dget() before calling follow_down(). On a negative return the error arm jumps to out without releasing those references:

err = follow_down(&path, follow_flags); if (err < 0) goto out;

Continue reading

follow_down() never drops the caller's entry-time refs on any error sub-case; for example a pre-cross d_manage() failure leaves path untouched, so the mntget()/dget() taken on entry survive the call.

Every other early-exit arm in nfsd_cross_mnt() (other-namespace return, IS_ERR(exp2), and the success tail after the swap) already calls path_put(&path); the err < 0 arm is the lone omission. The leak inflates mnt_count and d_count on each failed cross-mount, blocking umount and pinning dentries against the shrinker, and is reachable by any authenticated NFS client through nfsd_lookup_dentry or the NFSv4 READDIR encode path.

Fix by calling path_put(&path) before the goto out in the err < 0 arm so the entry-time refs are released on all follow_down() error returns.

Scores and how they were measured

CVSS base severity

7.5

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.6%

Scored Percentile 49.3%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-89707 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  4. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  5. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-89707, scored 2026-10-30. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 30). Linux kernel: nfsd: release path refs on follow_down() error (CVE-2026-89707). https://kevwire.com/record/CVE-2026-89707

MLA

"Linux kernel: nfsd: release path refs on follow_down() error (CVE-2026-89707)." KEVWire, 30 Oct. 2026, kevwire.com/record/CVE-2026-89707.

Chicago

KEVWire. "Linux kernel: nfsd: release path refs on follow_down() error (CVE-2026-89707)." Last modified October 30, 2026. https://kevwire.com/record/CVE-2026-89707.

Evidence summary (plain text)

Linux kernel: nfsd: release path refs on follow_down() error (Sep 11, 2026).
In the Linux kernel, the following vulnerability has been resolved:

nfsd: release path refs on follow_down() error

nfsd_cross_mnt() initializes a local struct path with mntget() and
dget() before calling follow_down(). On a negative return the error
arm jumps to out without releasing those references:

    err = follow_down(&path, follow_flags);
    if (err < 0)
            goto out;

follow_down() never drops the caller's entry-time refs on any error
sub-case; for example a pre-cross d_manage() failure leaves path
untouched, so the mntget()/dget() taken on entry survive the call.
CVSS 7.5 (version 3.1; evidence as of Oct 30, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-89707).
EPSS 0.6% for the following 30 days, scored Oct 30, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-89707&date=2026-10-30).
Sources:
NVD CVE-2026-89707: https://nvd.nist.gov/vuln/detail/CVE-2026-89707
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-30T13:06:45.042Z&lastModEndDate=2026-10-30T14:50:57.069Z&resultsPerPage=500&startIndex=500
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-30T12:22:16.957Z&lastModEndDate=2026-10-30T14:05:57.373Z&resultsPerPage=500&startIndex=500
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-30T11:45:59.009Z&lastModEndDate=2026-10-30T13:20:57.281Z&resultsPerPage=500&startIndex=500
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-89707&date=2026-10-30
Record ID: CVE-2026-89707.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 30, 2026, 14:52 UTC. Ingestion is not an independent editorial investigation.

NVD status: Received. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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Record details

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