CVE-2025-21972

Local service interruption via shared fragment reassembly

Published Apr 1, 2025 · Updated Aug 5, 2026

Memory leak in Linux kernel MCTP reassembly from 5.15 through 6.14-rc6 allows local users to interrupt service via cloned packets. mctp_frag_queue appends fragments to a frag_list that can remain shared with a cloned socket buffer, creating circular skb_shared_info references and incorrect reassembly. Reachability requires a driver that clones MCTP socket buffers; the CNA states that only the then-upcoming MCTP-over-USB driver does so.

CVSS severity5.5
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory leak in Linux kernel MCTP reassembly from 5.15 through 6.14-rc6 allows local users to interrupt service via cloned packets. mctp_frag_queue appends fragments to a frag_list that can remain shared with a cloned socket buffer, creating circular skb_shared_info references and incorrect reassembly. Reachability requires a driver that clones MCTP socket buffers; the CNA states that only the then-upcoming MCTP-over-USB driver does so.

The record

CVE
CVE-2025-21972
Published
Apr 1, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401, T1499.004
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=4a992bbd365094730a31bae1e12a6ca695336d57 <5c47d5bfa7b096cf8890afac32141c578583f8e0
  2. Affected versionversion=4a992bbd365094730a31bae1e12a6ca695336d57 <f44fff3d3c6cd67b6f348b821d73c4d6888c7a6e
  3. Affected versionversion=4a992bbd365094730a31bae1e12a6ca695336d57 <f5d83cf0eeb90fade4d5c4d17d24b8bee9ceeecc
  4. Affected versionversion=5.15

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4a992bbd365094730a31bae1e12a6ca695336d57 <5c47d5bfa7b096cf8890afac32141c578583f8e0; version=4a992bbd365094730a31bae1e12a6ca695336d57 <f44fff3d3c6cd67b6f348b821d73c4d6888c7a6e; version=4a992bbd365094730a31bae1e12a6ca695336d57 <f5d83cf0eeb90fade4d5c4d17d24b8bee9ceeecc; version=5.15

Published CVSS scores

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

CWE-401Missing Release of Memory after Effective Lifetime
T1499.004Application or System Exploitation

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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