{"id":"CVE-2025-40240","state":"PUBLISHED","title":"sctp: avoid NULL dereference when chunk data buffer is missing","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: avoid NULL dereference when chunk data buffer is missing\n\nchunk->skb pointer is dereferenced in the if-block where it's supposed\nto be NULL only.\n\nchunk->skb can only be NULL if chunk->head_skb is not. Check for frag_list\ninstead and do it just before replacing chunk->skb. We're sure that\notherwise chunk->skb is non-NULL because of outer if() condition.","publishedAt":"2025-12-04T15:31:29.715Z","updatedAt":"2026-08-05T12:08:44.117Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"61cda2777b07d27459f5cac5a047c3edf9c8a1a9","versionType":"git"},{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"08165c296597075763130919f2aae59b5822f016","versionType":"git"},{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"03e80a4b04ef1fb2c61dd63216ab8d3a5dcb196f","versionType":"git"},{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"4f6da435fb5d8a21cbf8cae5ca5a2ba0e1012b71","versionType":"git"},{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"cb9055ba30306ede4ad920002233d0659982f1cb","versionType":"git"},{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"7a832b0f99be19df608cb75c023f8027b1789bd1","versionType":"git"},{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"89b465b54227c245ddc7cc9ed822231af21123ef","versionType":"git"},{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"441f0647f7673e0e64d4910ef61a5fb8f16bfb82","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/inqueue.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.8","versionType":"semver"},{"version":"5.4.301","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.246","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.196","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.158","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.115","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.56","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.17.6","status":"unaffected","lessThanOrEqual":"6.17.*","versionType":"semver"},{"version":"6.18","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/inqueue.c"]}],"references":["https://git.kernel.org/stable/c/61cda2777b07d27459f5cac5a047c3edf9c8a1a9","https://git.kernel.org/stable/c/08165c296597075763130919f2aae59b5822f016","https://git.kernel.org/stable/c/03e80a4b04ef1fb2c61dd63216ab8d3a5dcb196f","https://git.kernel.org/stable/c/4f6da435fb5d8a21cbf8cae5ca5a2ba0e1012b71","https://git.kernel.org/stable/c/cb9055ba30306ede4ad920002233d0659982f1cb","https://git.kernel.org/stable/c/7a832b0f99be19df608cb75c023f8027b1789bd1","https://git.kernel.org/stable/c/89b465b54227c245ddc7cc9ed822231af21123ef","https://git.kernel.org/stable/c/441f0647f7673e0e64d4910ef61a5fb8f16bfb82"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/40xxx/CVE-2025-40240.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-40240","state":"PUBLISHED","datePublished":"2025-12-04T15:31:29.715Z","dateUpdated":"2026-08-05T12:08:44.117Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T07:20:57.181Z"},"containers":{"cna":{"title":"sctp: avoid NULL dereference when chunk data buffer is missing","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: avoid NULL dereference when chunk data buffer is missing\n\nchunk->skb pointer is dereferenced in the if-block where it's supposed\nto be NULL only.\n\nchunk->skb can only be NULL if chunk->head_skb is not. Check for frag_list\ninstead and do it just before replacing chunk->skb. We're sure that\notherwise chunk->skb is non-NULL because of outer if() condition."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"61cda2777b07d27459f5cac5a047c3edf9c8a1a9","versionType":"git"},{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"08165c296597075763130919f2aae59b5822f016","versionType":"git"},{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"03e80a4b04ef1fb2c61dd63216ab8d3a5dcb196f","versionType":"git"},{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"4f6da435fb5d8a21cbf8cae5ca5a2ba0e1012b71","versionType":"git"},{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"cb9055ba30306ede4ad920002233d0659982f1cb","versionType":"git"},{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"7a832b0f99be19df608cb75c023f8027b1789bd1","versionType":"git"},{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"89b465b54227c245ddc7cc9ed822231af21123ef","versionType":"git"},{"version":"90017accff61ae89283ad9a51f9ac46ca01633fb","status":"affected","lessThan":"441f0647f7673e0e64d4910ef61a5fb8f16bfb82","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/inqueue.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.8","versionType":"semver"},{"version":"5.4.301","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.246","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.196","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.158","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.115","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.56","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.17.6","status":"unaffected","lessThanOrEqual":"6.17.*","versionType":"semver"},{"version":"6.18","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sctp/inqueue.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/61cda2777b07d27459f5cac5a047c3edf9c8a1a9"},{"url":"https://git.kernel.org/stable/c/08165c296597075763130919f2aae59b5822f016"},{"url":"https://git.kernel.org/stable/c/03e80a4b04ef1fb2c61dd63216ab8d3a5dcb196f"},{"url":"https://git.kernel.org/stable/c/4f6da435fb5d8a21cbf8cae5ca5a2ba0e1012b71"},{"url":"https://git.kernel.org/stable/c/cb9055ba30306ede4ad920002233d0659982f1cb"},{"url":"https://git.kernel.org/stable/c/7a832b0f99be19df608cb75c023f8027b1789bd1"},{"url":"https://git.kernel.org/stable/c/89b465b54227c245ddc7cc9ed822231af21123ef"},{"url":"https://git.kernel.org/stable/c/441f0647f7673e0e64d4910ef61a5fb8f16bfb82"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The bug is in the SCTP packet input path (`sctp_rcv` → `sctp_inq_push` → `sctp_assoc_bh_rcv` → `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)->frag_list` on a shared/cloned GSO skb, and the attacker controls both sides — generating the large GSO SCTP packets and the concurrent clone/consumer that mutates the shared shinfo — 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 — 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's 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->dev`) that immediately oopses; no attacker-controlled memory is read back or returned to userspace.\nI:N - Nothing is written — 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."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:08:44.117Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"5.4.301"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"5.10.246"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"5.15.196"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"6.1.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"6.6.115"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"6.12.56"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"6.17.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"6.18"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-16T19:41:12.884839Z","id":"CVE-2025-40240","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-06-16T19:41:24.741Z"}}]}}}