CVE-2025-40240Network attack vector

Remote kernel crash via SCTP NULL dereference

Published Dec 4, 2025 · Updated Aug 5, 2026

NULL-pointer dereference in the Linux kernel SCTP subsystem allows remote attackers to crash systems through SCTP traffic. Within net/sctp/inqueue.c, the chunk reassembly path dereferences chunk->skb inside a branch reached when that pointer is NULL, rather than checking the fragment list on chunk->head_skb before replacing chunk->skb. Network access to an enabled SCTP endpoint is required; exploitation interrupts service without reported data disclosure or modification.

CVSS severity7.5
High
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL-pointer dereference in the Linux kernel SCTP subsystem allows remote attackers to crash systems through SCTP traffic. Within net/sctp/inqueue.c, the chunk reassembly path dereferences chunk->skb inside a branch reached when that pointer is NULL, rather than checking the fragment list on chunk->head_skb before replacing chunk->skb. Network access to an enabled SCTP endpoint is required; exploitation interrupts service without reported data disclosure or modification.

The record

CVE
CVE-2025-40240
Published
Dec 4, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 4, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=4.8
  2. Affected versionversion=90017accff61ae89283ad9a51f9ac46ca01633fb <03e80a4b04ef1fb2c61dd63216ab8d3a5dcb196f
  3. Affected versionversion=90017accff61ae89283ad9a51f9ac46ca01633fb <08165c296597075763130919f2aae59b5822f016
  4. Affected versionversion=90017accff61ae89283ad9a51f9ac46ca01633fb <441f0647f7673e0e64d4910ef61a5fb8f16bfb82
  5. Affected versionversion=90017accff61ae89283ad9a51f9ac46ca01633fb <4f6da435fb5d8a21cbf8cae5ca5a2ba0e1012b71
  6. Affected versionversion=90017accff61ae89283ad9a51f9ac46ca01633fb <61cda2777b07d27459f5cac5a047c3edf9c8a1a9
  7. Affected versionversion=90017accff61ae89283ad9a51f9ac46ca01633fb <7a832b0f99be19df608cb75c023f8027b1789bd1
  8. Affected versionversion=90017accff61ae89283ad9a51f9ac46ca01633fb <89b465b54227c245ddc7cc9ed822231af21123ef
  9. Affected versionversion=90017accff61ae89283ad9a51f9ac46ca01633fb <cb9055ba30306ede4ad920002233d0659982f1cb

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.8; version=90017accff61ae89283ad9a51f9ac46ca01633fb <03e80a4b04ef1fb2c61dd63216ab8d3a5dcb196f; version=90017accff61ae89283ad9a51f9ac46ca01633fb <08165c296597075763130919f2aae59b5822f016; version=90017accff61ae89283ad9a51f9ac46ca01633fb <441f0647f7673e0e64d4910ef61a5fb8f16bfb82; version=90017accff61ae89283ad9a51f9ac46ca01633fb <4f6da435fb5d8a21cbf8cae5ca5a2ba0e1012b71; version=90017accff61ae89283ad9a51f9ac46ca01633fb <61cda2777b07d27459f5cac5a047c3edf9c8a1a9; version=90017accff61ae89283ad9a51f9ac46ca01633fb <7a832b0f99be19df608cb75c023f8027b1789bd1; version=90017accff61ae89283ad9a51f9ac46ca01633fb <89b465b54227c245ddc7cc9ed822231af21123ef; version=90017accff61ae89283ad9a51f9ac46ca01633fb <cb9055ba30306ede4ad920002233d0659982f1cb

Published CVSS scores

7.5Linux Kernel CNACVSS: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

T1499.004Endpoint Denial of Service: Application 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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