CVE-2023-54085Network attack vector

Remote system crash via MPTCP fast-open dereference

Published Dec 24, 2025 · Updated Dec 24, 2025

A NULL pointer dereference in Linux kernel 6.2 before 6.2.12 allows remote attackers to crash systems via MPTCP fast open. In net/mptcp/fastopen.c, early TCP fallback deletes the subflow context, but subflow_prep_synack() then dereferences that NULL context. A routable peer needs an MPTCP listening socket and a TCP Fast Open SYN carrying data without MPTCP options; the pre-authentication fault causes a repeatable full-system crash.

CVSS severity7.5
High
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A NULL pointer dereference in Linux kernel 6.2 before 6.2.12 allows remote attackers to crash systems via MPTCP fast open. In net/mptcp/fastopen.c, early TCP fallback deletes the subflow context, but subflow_prep_synack() then dereferences that NULL context. A routable peer needs an MPTCP listening socket and a TCP Fast Open SYN carrying data without MPTCP options; the pre-authentication fault causes a repeatable full-system crash.

The record

CVE
CVE-2023-54085
Published
Dec 24, 2025
Updated
Dec 24, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 24, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 24, 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=36b122baf6a8bd46b4a591f12f4ed17b22257408 <95135835519b0ab931c39908b2c99e9fb3c9068b
  2. Affected versionversion=36b122baf6a8bd46b4a591f12f4ed17b22257408 <c0ff6f6da66a7791a32c0234388b1bdc00244917
  3. Affected versionversion=6.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=36b122baf6a8bd46b4a591f12f4ed17b22257408 <95135835519b0ab931c39908b2c99e9fb3c9068b; version=36b122baf6a8bd46b4a591f12f4ed17b22257408 <c0ff6f6da66a7791a32c0234388b1bdc00244917; version=6.2

Published CVSS scores

7.5Linux Kernel CVE TeamCVSS:3.1/AV:N/AC:L/PR:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

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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