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CVE Record

CVE-2025-40240: sctp: avoid NULL dereference when chunk data buffer is missing

In the Linux kernel, the following vulnerability has been resolved: sctp: avoid NULL dereference when chunk data buffer is missing chunk->skb pointer is dereferenced in the if-block where it's supposed to be NULL only. chunk->skb can only be NULL if chunk->head_skb is not. Check for frag_list instead and do it just before replacing chunk->skb. We're sure that otherwise chunk->skb is non-NULL because of outer if() condition.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2025-40240 is a Linux kernel SCTP flaw involving a missing chunk data buffer. The public record describes a NULL pointer dereference, which can cause kernel instability. No CVSS score, CWE, or active exploitation evidence is provided in the source bundle.

Executive priority

Treat as a kernel maintenance priority, not an emergency, unless SCTP is exposed on critical systems. The lack of severity score and exploitation evidence lowers urgency, but kernel NULL dereferences can still affect availability.

Technical view

The fix changes SCTP chunk handling so code does not dereference chunk->skb when it may be NULL. The record says chunk->skb can be NULL only when chunk->head_skb is present, and the corrected logic checks frag_list before replacing chunk->skb.

Likely exposure

Exposure is most relevant to Linux systems running affected kernel versions with SCTP code present or used. The bundle lists Linux as affected, but version-range semantics are incomplete, so distribution-specific advisories should determine exact exposure.

Exploitation context

The provided sources do not claim public exploitation, weaponized proof of concept, or CISA KEV listing. Impact is described only as a NULL dereference in kernel SCTP handling, so exploitation assumptions should remain conservative.

Researcher notes

The available record is sparse: no CVSS, CWE, attack vector, or explicit affected range semantics. Analysis should focus on the upstream stable commits and downstream vendor mapping before making claims about reachability or impact.

Mitigation direction

  • Check your Linux distribution advisory for CVE-2025-40240 applicability.
  • Apply kernel updates that include the referenced stable SCTP fix.
  • Prioritize systems where SCTP is enabled, exposed, or business-critical.
  • Track vendor backports rather than relying only on upstream version numbers.

Validation and detection

  • Inventory Linux kernel versions across servers, appliances, and containers hosts.
  • Confirm whether SCTP support is enabled or used in exposed services.
  • Map installed kernels to vendor advisories for CVE-2025-40240.
  • Verify deployed kernels include the relevant stable patch or vendor backport.
Prepared
Confidence
medium
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2025-40240 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
1ADP providers
9Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux90017accff61ae89283ad9a51f9ac46ca01633fb, 90017accff61ae89283ad9a51f9ac46ca01633fb, 90017accff61ae89283ad9a51f9ac46ca01633fb, 90017accff61ae89283ad9a51f9ac46ca01633fb, 90017accff61ae89283ad9a51f9ac46ca01633fb, 90017accff61ae89283ad9a51f9ac46ca01633fb, 90017accff61ae89283ad9a51f9ac46ca01633fb, 90017accff61ae89283ad9a51f9ac46ca01633fbunaffected
LinuxLinux4.8, 0, 5.4.301, 5.10.246, 5.15.196, 6.1.158, 6.6.115, 6.12.56, 6.17.6, 6.18affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.