CVE-2025-40240 (GCVE-0-2025-40240)
Vulnerability from cvelistv5 – Published: 2025-12-04 15:31 – Updated: 2026-08-05 12:08
VLAI
EPSS
VEX
Title
sctp: avoid NULL dereference when chunk data buffer is missing
Summary
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.
Severity
7.5 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-16 19:41 UTC
Assigner
References
8 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
90017accff61ae89283ad9a51f9ac46ca01633fb , < 61cda2777b07d27459f5cac5a047c3edf9c8a1a9
(git)
Affected: 90017accff61ae89283ad9a51f9ac46ca01633fb , < 08165c296597075763130919f2aae59b5822f016 (git) Affected: 90017accff61ae89283ad9a51f9ac46ca01633fb , < 03e80a4b04ef1fb2c61dd63216ab8d3a5dcb196f (git) Affected: 90017accff61ae89283ad9a51f9ac46ca01633fb , < 4f6da435fb5d8a21cbf8cae5ca5a2ba0e1012b71 (git) Affected: 90017accff61ae89283ad9a51f9ac46ca01633fb , < cb9055ba30306ede4ad920002233d0659982f1cb (git) Affected: 90017accff61ae89283ad9a51f9ac46ca01633fb , < 7a832b0f99be19df608cb75c023f8027b1789bd1 (git) Affected: 90017accff61ae89283ad9a51f9ac46ca01633fb , < 89b465b54227c245ddc7cc9ed822231af21123ef (git) Affected: 90017accff61ae89283ad9a51f9ac46ca01633fb , < 441f0647f7673e0e64d4910ef61a5fb8f16bfb82 (git) |
guessed | |
| Linux | Linux |
Affected:
4.8
Unaffected: 0 , < 4.8 (semver) Unaffected: 5.4.301 , ≤ 5.4.* (semver) Unaffected: 5.10.246 , ≤ 5.10.* (semver) Unaffected: 5.15.196 , ≤ 5.15.* (semver) Unaffected: 6.1.158 , ≤ 6.1.* (semver) Unaffected: 6.6.115 , ≤ 6.6.* (semver) Unaffected: 6.12.56 , ≤ 6.12.* (semver) Unaffected: 6.17.6 , ≤ 6.17.* (semver) Unaffected: 6.18 , ≤ * (original_commit_for_fix) |
guessed |
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: avoid NULL dereference when chunk data buffer is missing\n\nchunk-\u003eskb pointer is dereferenced in the if-block where it\u0027s supposed\nto be NULL only.\n\nchunk-\u003eskb can only be NULL if chunk-\u003ehead_skb is not. Check for frag_list\ninstead and do it just before replacing chunk-\u003eskb. We\u0027re sure that\notherwise chunk-\u003eskb is non-NULL because of outer if() condition."
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"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nsctp: evitar la desreferenciaci\u00f3n NULL cuando falta el b\u00fafer de datos del chunk\n\nEl puntero chunk -\u003e skb es desreferenciado en el bloque if donde se supone que solo debe ser NULL.\n\nchunk -\u003e skb solo puede ser NULL si chunk -\u003e head_skb no lo es. Comprobar frag_list en su lugar y hacerlo justo antes de reemplazar chunk -\u003e skb. Estamos seguros de que de lo contrario chunk -\u003e skb no es NULL debido a la condici\u00f3n if() externa."
}
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"scope": "UNCHANGED",
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"redhat_vex": {
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"current_release_date": "2026-10-31T21:19:29+00:00",
"cve": "CVE-2025-40240",
"id": "CVE-2025-40240",
"initial_release_date": "2025-12-04T00:00:00+00:00",
"product_status:fixed": "2366",
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"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: sctp: avoid NULL dereference when chunk data buffer is missing",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40240.json",
"version": "3"
},
"vulnrichment": {
"containers": {
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{
"metrics": [
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"other": {
"content": {
"id": "CVE-2025-40240",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-06-16T19:41:12.884839Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-06-16T19:41:19.307Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
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{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"versionType": "git"
},
{
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{
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"status": "affected",
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"vendor": "Linux",
"versions": [
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"version": "4.8"
},
{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
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{
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"status": "unaffected",
"version": "5.4.301",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.246",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.196",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.1.158",
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},
{
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"status": "unaffected",
"version": "6.6.115",
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{
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"status": "unaffected",
"version": "6.12.56",
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{
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"status": "unaffected",
"version": "6.17.6",
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{
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"status": "unaffected",
"version": "6.18",
"versionType": "original_commit_for_fix"
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}
],
"cpeApplicability": [
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "4.8",
"vulnerable": true
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{
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: avoid NULL dereference when chunk data buffer is missing\n\nchunk-\u003eskb pointer is dereferenced in the if-block where it\u0027s supposed\nto be NULL only.\n\nchunk-\u003eskb can only be NULL if chunk-\u003ehead_skb is not. Check for frag_list\ninstead and do it just before replacing chunk-\u003eskb. We\u0027re sure that\notherwise chunk-\u003eskb is non-NULL because of outer if() condition."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.5,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"scenarios": [
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"lang": "en",
"value": "AV:N - The bug is in the SCTP packet input path (`sctp_rcv` \u2192 `sctp_inq_push` \u2192 `sctp_assoc_bh_rcv` \u2192 `sctp_inq_pop`), processing chunk data supplied by a peer over IP; the vulnerable component is bound to the network stack and is driven entirely by received SCTP packets, including from a container/veth peer on the other side of a security boundary.\nAC:L - The trigger is a re-read of `skb_shinfo(skb)-\u003efrag_list` on a shared/cloned GSO skb, and the attacker controls both sides \u2014 generating the large GSO SCTP packets and the concurrent clone/consumer that mutates the shared shinfo \u2014 which is exactly the pattern syzbot reproduced for the sibling bug in the same lines of `sctp_inq_pop()`.\nPR:N - `sctp_inq_pop()` runs before any chunk is validated by the state machine \u2014 OOTB packets and INIT chunks from a completely unauthenticated peer reach it, and no capability or credential check exists anywhere on the `sctp_rcv()` path.\nUI:N - Processing happens automatically in softirq/backlog context as soon as the packets are received; no victim action of any kind is needed.\nS:U - The NULL dereference faults inside the kernel\u0027s own SCTP receive processing; no hypervisor, IOMMU, or sandbox boundary is crossed.\nC:N - The fault is a read of an unmapped low address (`NULL-\u003edev`) that immediately oopses; no attacker-controlled memory is read back or returned to userspace.\nI:N - Nothing is written \u2014 the bug is a read of a NULL pointer field, so no kernel memory is modified and no control-flow hijack primitive is produced.\nA:H - The path first hits `WARN_ON()` (an immediate panic on `panic_on_warn=1` systems, common on hardened/cloud kernels) and then dereferences NULL, producing a kernel oops in softirq/backlog context that kills SCTP receive processing and typically brings down the machine; it is repeatable by simply resending traffic."
}
]
}
],
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"url": "https://git.kernel.org/stable/c/08165c296597075763130919f2aae59b5822f016"
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"url": "https://git.kernel.org/stable/c/4f6da435fb5d8a21cbf8cae5ca5a2ba0e1012b71"
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"url": "https://git.kernel.org/stable/c/cb9055ba30306ede4ad920002233d0659982f1cb"
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{
"url": "https://git.kernel.org/stable/c/89b465b54227c245ddc7cc9ed822231af21123ef"
},
{
"url": "https://git.kernel.org/stable/c/441f0647f7673e0e64d4910ef61a5fb8f16bfb82"
}
],
"title": "sctp: avoid NULL dereference when chunk data buffer is missing",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2025-40240",
"datePublished": "2025-12-04T15:31:29.715Z",
"dateReserved": "2025-04-16T07:20:57.181Z",
"dateUpdated": "2026-08-05T12:08:44.117Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
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}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
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- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.