CVE-2026-52990

Local unmount hang via leaked inode reference

Published Jun 24, 2026 · Updated Jun 24, 2026

Race condition in the Linux Kernel fsnotify subsystem allows local users to hang unmount operations through concurrent mark changes. fsnotify_recalc_mask() discards an inode pointer returned by __fsnotify_recalc_mask() when HAS_IREF changes from set to clear, so the required object release never occurs. Low-privileged local access and the add-mark/detach-mark race are required; successful triggering blocks filesystem teardown without reported data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in the Linux Kernel fsnotify subsystem allows local users to hang unmount operations through concurrent mark changes. fsnotify_recalc_mask() discards an inode pointer returned by __fsnotify_recalc_mask() when HAS_IREF changes from set to clear, so the required object release never occurs. Low-privileged local access and the add-mark/detach-mark race are required; successful triggering blocks filesystem teardown without reported data disclosure or modification.

The record

CVE
CVE-2026-52990
Published
Jun 24, 2026
Updated
Jun 24, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4f145b67c075324b13d6ae7d5abb6e7a1dbac26d
  2. Affected versionversion=5.10.220 <5.11
  3. Affected versionversion=5.15.154 <5.16
  4. Affected versionversion=5.19
  5. Affected versionversion=c3638b5b13740fa31762d414bbce8b7a694e582a <4aca914ac152f5d055ddcb36704d1e539ac08977
  6. Affected versionversion=c3638b5b13740fa31762d414bbce8b7a694e582a <5c80289503da3658e3df80280598c68d181eadbd
  7. Affected versionversion=c3638b5b13740fa31762d414bbce8b7a694e582a <8c8afa6444e6bdc145d2bf2f3aeeca6da3e36b42
  8. Affected versionversion=c3638b5b13740fa31762d414bbce8b7a694e582a <b740cc86816bbc87902ae9db74cd21abde3c8d63
  9. Affected versionversion=ff34ebaa6f6dc1eebce6a8d6f12a1566f33d00fe

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=4f145b67c075324b13d6ae7d5abb6e7a1dbac26d; version=5.10.220 <5.11; version=5.15.154 <5.16; version=5.19; version=c3638b5b13740fa31762d414bbce8b7a694e582a <4aca914ac152f5d055ddcb36704d1e539ac08977; version=c3638b5b13740fa31762d414bbce8b7a694e582a <5c80289503da3658e3df80280598c68d181eadbd; version=c3638b5b13740fa31762d414bbce8b7a694e582a <8c8afa6444e6bdc145d2bf2f3aeeca6da3e36b42; version=c3638b5b13740fa31762d414bbce8b7a694e582a <b740cc86816bbc87902ae9db74cd21abde3c8d63; version=ff34ebaa6f6dc1eebce6a8d6f12a1566f33d00fe

Published CVSS scores

4.7Amazon LinuxCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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