CVE-2025-21896

Local privilege escalation via FUSE folio use-after-free

Published Apr 1, 2025 · Updated Aug 5, 2026

Use-after-free in Linux kernel FUSE readahead in 6.13 before 6.13.6 allows local users to read or modify kernel memory. The folio conversion drops its reference after locking, but fuse_try_move_page() later assumes ap->folios still owns that reference during splice-page replacement. An unprivileged account can mount a FUSE filesystem, send SPLICE_F_MOVE replies through its daemon, and drive readahead to cause stale-page access, double-free, privilege escalation, or a kernel panic.

CVSS severity7.8
High
EPSS probability0.21%
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 kernel FUSE readahead in 6.13 before 6.13.6 allows local users to read or modify kernel memory. The folio conversion drops its reference after locking, but fuse_try_move_page() later assumes ap->folios still owns that reference during splice-page replacement. An unprivileged account can mount a FUSE filesystem, send SPLICE_F_MOVE replies through its daemon, and drive readahead to cause stale-page access, double-free, privilege escalation, or a kernel panic.

The record

CVE
CVE-2025-21896
Published
Apr 1, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 1, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=3eab9d7bc2f4ae7f3f9c9c7852ff61600df79856 <0c67c37e1710b2a8f61c8a02db95a51fe577e2c1
  2. Affected versionversion=3eab9d7bc2f4ae7f3f9c9c7852ff61600df79856 <60db11f1b7fba4a66b117ea998d965818784a98d
  3. Affected versionversion=6.13

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3eab9d7bc2f4ae7f3f9c9c7852ff61600df79856 <0c67c37e1710b2a8f61c8a02db95a51fe577e2c1; version=3eab9d7bc2f4ae7f3f9c9c7852ff61600df79856 <60db11f1b7fba4a66b117ea998d965818784a98d; version=6.13

Published CVSS scores

7.8Linux kernel CNACVSS:3.1/AV:L/AC:L/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 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

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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