{"id":"CVE-2025-39718","state":"PUBLISHED","title":"vsock/virtio: Validate length in packet header before skb_put()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nvsock/virtio: Validate length in packet header before skb_put()\n\nWhen receiving a vsock packet in the guest, only the virtqueue buffer\nsize is validated prior to virtio_vsock_skb_rx_put(). Unfortunately,\nvirtio_vsock_skb_rx_put() uses the length from the packet header as the\nlength argument to skb_put(), potentially resulting in SKB overflow if\nthe host has gone wonky.\n\nValidate the length as advertised by the packet header before calling\nvirtio_vsock_skb_rx_put().","publishedAt":"2025-09-05T17:21:25.959Z","updatedAt":"2026-10-15T22:02:30.928Z","severity":{"score":8.4,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"baddcc2c71572968cdaeee1c4ab3dc0ad90fa765","status":"affected","lessThan":"969b06bd8b7560efb100a34227619e7d318fbe05","versionType":"git"},{"version":"71dc9ec9ac7d3eee785cdc986c3daeb821381e20","status":"affected","lessThan":"ee438c492b2e0705d819ac0e25d04fae758d8f8f","versionType":"git"},{"version":"71dc9ec9ac7d3eee785cdc986c3daeb821381e20","status":"affected","lessThan":"faf332a10372390ce65d0b803888f4b25a388335","versionType":"git"},{"version":"71dc9ec9ac7d3eee785cdc986c3daeb821381e20","status":"affected","lessThan":"676f03760ca1d69c2470cef36c44dc152494b47c","versionType":"git"},{"version":"71dc9ec9ac7d3eee785cdc986c3daeb821381e20","status":"affected","lessThan":"0dab92484474587b82e8e0455839eaf5ac7bf894","versionType":"git"},{"version":"6.1.63","status":"affected","lessThan":"6.1.149","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/vmw_vsock/virtio_transport.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.3","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.3","versionType":"semver"},{"version":"6.1.149","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.103","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.44","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.16.4","status":"unaffected","lessThanOrEqual":"6.16.*","versionType":"semver"},{"version":"6.17","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/vmw_vsock/virtio_transport.c"]}],"references":["https://git.kernel.org/stable/c/969b06bd8b7560efb100a34227619e7d318fbe05","https://git.kernel.org/stable/c/ee438c492b2e0705d819ac0e25d04fae758d8f8f","https://git.kernel.org/stable/c/faf332a10372390ce65d0b803888f4b25a388335","https://git.kernel.org/stable/c/676f03760ca1d69c2470cef36c44dc152494b47c","https://git.kernel.org/stable/c/0dab92484474587b82e8e0455839eaf5ac7bf894","https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html","https://cert-portal.siemens.com/productcert/html/ssa-032379.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/39xxx/CVE-2025-39718.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-39718","state":"PUBLISHED","datePublished":"2025-09-05T17:21:25.959Z","dateUpdated":"2026-10-15T22:02:30.928Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T07:20:57.117Z"},"containers":{"cna":{"title":"vsock/virtio: Validate length in packet header before skb_put()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nvsock/virtio: Validate length in packet header before skb_put()\n\nWhen receiving a vsock packet in the guest, only the virtqueue buffer\nsize is validated prior to virtio_vsock_skb_rx_put(). Unfortunately,\nvirtio_vsock_skb_rx_put() uses the length from the packet header as the\nlength argument to skb_put(), potentially resulting in SKB overflow if\nthe host has gone wonky.\n\nValidate the length as advertised by the packet header before calling\nvirtio_vsock_skb_rx_put()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"baddcc2c71572968cdaeee1c4ab3dc0ad90fa765","status":"affected","lessThan":"969b06bd8b7560efb100a34227619e7d318fbe05","versionType":"git"},{"version":"71dc9ec9ac7d3eee785cdc986c3daeb821381e20","status":"affected","lessThan":"ee438c492b2e0705d819ac0e25d04fae758d8f8f","versionType":"git"},{"version":"71dc9ec9ac7d3eee785cdc986c3daeb821381e20","status":"affected","lessThan":"faf332a10372390ce65d0b803888f4b25a388335","versionType":"git"},{"version":"71dc9ec9ac7d3eee785cdc986c3daeb821381e20","status":"affected","lessThan":"676f03760ca1d69c2470cef36c44dc152494b47c","versionType":"git"},{"version":"71dc9ec9ac7d3eee785cdc986c3daeb821381e20","status":"affected","lessThan":"0dab92484474587b82e8e0455839eaf5ac7bf894","versionType":"git"},{"version":"6.1.63","status":"affected","lessThan":"6.1.149","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/vmw_vsock/virtio_transport.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.3","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.3","versionType":"semver"},{"version":"6.1.149","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.103","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.44","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.16.4","status":"unaffected","lessThanOrEqual":"6.16.*","versionType":"semver"},{"version":"6.17","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/vmw_vsock/virtio_transport.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/969b06bd8b7560efb100a34227619e7d318fbe05"},{"url":"https://git.kernel.org/stable/c/ee438c492b2e0705d819ac0e25d04fae758d8f8f"},{"url":"https://git.kernel.org/stable/c/faf332a10372390ce65d0b803888f4b25a388335"},{"url":"https://git.kernel.org/stable/c/676f03760ca1d69c2470cef36c44dc152494b47c"},{"url":"https://git.kernel.org/stable/c/0dab92484474587b82e8e0455839eaf5ac7bf894"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":8.4,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The attack surface is the virtio-vsock RX virtqueue, which is host/hypervisor-local to the guest rather than network-reachable; vsock carries no routed network traffic. This matches the kernel CNA convention of AV:L for malicious-virtio-backend attacks on guest drivers.\nAC:L - The backend simply writes an arbitrary 32-bit value into the packet header's len field; no race, no memory-layout dependency, and the wraparound window that defeats skb_over_panic() is a fixed, deterministic 44-value range. Every trigger condition is fully under the attacker's control.\nPR:N - No privileges exist in the vulnerable component — the guest kernel — for the attacker to hold; virtio_transport_rx_work() consumes the buffer from a workqueue as soon as the device completes it, with no guest socket, user, or capability involved. Userspace VMMs (Firecracker, crosvm, vhost-user-vsock) are deliberately deprivileged, and under SEV-SNP/TDX/CCA the host is untrusted by design.\nUI:N - The RX work item processes the malicious buffer automatically on device completion, and the vsockmon tap path runs before any socket lookup. No guest user opens a socket, reads data, or performs any action.\nS:U - The vulnerable component and every impacted resource are the guest kernel and its own userspace, which share one security authority. Consistent with the S:U precedent for device→guest virtio driver bugs (CVE-2026-46123, CVE-2026-64456, CVE-2026-64490); S:C in this subsystem has been reserved for guest→host direction.\nC:H - A header len exceeding the bytes the device actually wrote makes skb_put() expose uninitialized kmalloc-8k slab contents, which recvmsg() copies straight to guest userspace, and the u32-wrap case leaves skb->len at ~4 GiB so skb_copy_datagram_iter() reads essentially unbounded guest kernel memory. Repeatable per packet with heap grooming, this is an arbitrary kernel-memory read.\nI:H - The wraparound bypasses skb_over_panic() and leaves a corrupted skb whose len/tail are desynchronized from the allocation; virtio_transport_build_skb() then truncates the size_t allocation size to 75 bytes and performs skb_put_data() of 0xFFFFFFFF, an unbounded out-of-bounds memcpy write out of a small slab object. Combined with the read primitive this is a heap-corruption primitive suitable for control-flow hijack in the guest.\nA:H - Any header len outside the narrow wrap window drives skb->tail past skb->end, hitting skb_over_panic() → BUG() in the virtio_vsock workqueue, and the wrap path instead faults on a multi-gigabyte copy. Either way the guest kernel oopses or panics, triggerable at will and repeatedly."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:04:50.190Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.63","versionEndExcluding":"6.1.149"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.6.103"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.12.44"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.16.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.17"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CVE Program Container","references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2025-11-03T17:42:44.024Z"}},{"affected":[{"vendor":"Siemens","product":"SIMATIC CN 4100","defaultStatus":"unknown","versions":[{"version":"0","status":"affected","lessThan":"V5.0","versionType":"custom"}]}],"references":[{"url":"https://cert-portal.siemens.com/productcert/html/ssa-032379.html"}],"providerMetadata":{"shortName":"siemens-SADP","orgId":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","dateUpdated":"2026-05-12T12:06:34.737Z"},"x_adpType":"supplier"},{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2025-39718","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-15T21:53:42.566432Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-15T22:02:30.928Z"}}]}}}