CVE-2025-39717

Local kernel-memory corruption via detached-mount id-map race

Published Sep 5, 2025 · Updated Sep 5, 2025

Use-after-free in Linux 6.15 through 6.16.3 allows local users to read and corrupt kernel memory through mount id-mapping operations. fs/namespace.c lets open_tree_attr() replace the id-mapping of a detached visible mount when OPEN_TREE_CLONE is absent, freeing a struct mnt_idmap while concurrent operations can retain stale references. An unprivileged user namespace supplies the required mount capabilities; racing those references can expose kernel memory, alter permission decisions, or panic the host.

CVSS severity7.8
High
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux 6.15 through 6.16.3 allows local users to read and corrupt kernel memory through mount id-mapping operations. fs/namespace.c lets open_tree_attr() replace the id-mapping of a detached visible mount when OPEN_TREE_CLONE is absent, freeing a struct mnt_idmap while concurrent operations can retain stale references. An unprivileged user namespace supplies the required mount capabilities; racing those references can expose kernel memory, alter permission decisions, or panic the host.

The record

CVE
CVE-2025-39717
Published
Sep 5, 2025
Updated
Sep 5, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 5, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 5, 2025Record 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=2462651ffa76b87f9c2e4403ef6e6b89b703fb2f <69dbdc711d9130136824e3830191a6afffa0a1f0
  2. Affected versionversion=2462651ffa76b87f9c2e4403ef6e6b89b703fb2f <9308366f062129d52e0ee3f7a019f7dd41db33df
  3. Affected versionversion=6.15

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2462651ffa76b87f9c2e4403ef6e6b89b703fb2f <69dbdc711d9130136824e3830191a6afffa0a1f0; version=2462651ffa76b87f9c2e4403ef6e6b89b703fb2f <9308366f062129d52e0ee3f7a019f7dd41db33df; version=6.15

Published CVSS scores

7.8Linux CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.0Red HatCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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