{"id":"CVE-2025-21669","state":"PUBLISHED","title":"vsock/virtio: discard packets if the transport changes","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nvsock/virtio: discard packets if the transport changes\n\nIf the socket has been de-assigned or assigned to another transport,\nwe must discard any packets received because they are not expected\nand would cause issues when we access vsk->transport.\n\nA possible scenario is described by Hyunwoo Kim in the attached link,\nwhere after a first connect() interrupted by a signal, and a second\nconnect() failed, we can find `vsk->transport` at NULL, leading to a\nNULL pointer dereference.","publishedAt":"2025-01-31T11:25:33.185Z","updatedAt":"2026-10-15T01:02:55.148Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux 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discard packets if the transport changes","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nvsock/virtio: discard packets if the transport changes\n\nIf the socket has been de-assigned or assigned to another transport,\nwe must discard any packets received because they are not expected\nand would cause issues when we access vsk->transport.\n\nA possible scenario is described by Hyunwoo Kim in the attached link,\nwhere after a first connect() interrupted by a signal, and a second\nconnect() failed, we can find `vsk->transport` at NULL, leading to a\nNULL pointer 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- The vulnerability is reached through AF_VSOCK socket syscalls (`connect()`) plus packets delivered by the local `vsock_loopback` transport, all from a local process. Per kernel scoring guidance vsock is Local.\nAC:L - The attacker controls every element: both `connect()` calls, the interrupting signal (self-delivered via `alarm()`/`pthread_kill()`), the peer socket that times the RESPONSE, and the RST/SHUTDOWN packet, and the sequence can be retried indefinitely.\nPR:L - `vsock_create()` performs no capability check and `CONFIG_VSOCKETS_LOOPBACK` is `default y`, so any unprivileged local user can create AF_VSOCK sockets, auto-bind an ephemeral port, and inject loopback packets.\nUI:N - The entire sequence — double connect, signal, packet injection — is performed by the attacker's own process with no victim action required.\nS:U - The corruption and crash are confined to the kernel of the machine running the attacker's process; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - When the socket has been reassigned to a non-virtio transport, `vsk->trans` is type-confused as `struct virtio_vsock_sock`, letting the receive path read and act on mistyped heap state (mistyped `sk_buff_head` in `virtio_transport_recv_enqueue()`, `container_of` on a non-`virtio_transport` ops struct), which is leverageable for arbitrary kernel memory disclosure.\nI:H - The same type confusion writes two fully attacker-controlled 32-bit header values (`buf_alloc`/`fwd_cnt`) into the middle of a differently-typed heap object (over `qpair`/`produce_size` in `struct vmci_transport`) and performs an indirect call through `t_ops->send_pkt` derived from a bogus `container_of`, giving a controlled-write and control-flow hijack primitive.\nA:H - The confirmed and reported impact is a NULL pointer dereference at `vsk->transport->stream_has_data()` while the socket lock is held, producing a kernel oops/panic that an unprivileged user can trigger on demand."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T11:53:30.113Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"5.10.234"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"5.15.177"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"6.1.127"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"6.6.74"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"6.12.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"6.13"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":5.5,"attackVector":"LOCAL","baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"LOW","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"id":"CVE-2025-21669","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2025-10-01T19:52:17.860929Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-476","lang":"en","type":"CWE","description":"CWE-476 NULL Pointer Dereference"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2025-10-01T19:57:12.459Z"}},{"title":"CVE Program Container","references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html"},{"url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2025-11-03T20:58:50.209Z"}},{"affected":[{"vendor":"Siemens","product":"SIMATIC S7-1500 TM MFP - GNU/Linux subsystem","defaultStatus":"unknown","versions":[{"version":"0","status":"affected","lessThan":"*","versionType":"custom"}]}],"references":[{"url":"https://cert-portal.siemens.com/productcert/html/ssa-265688.html"}],"providerMetadata":{"shortName":"siemens-SADP","orgId":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","dateUpdated":"2026-10-15T01:02:55.148Z"},"x_adpType":"supplier"}]}}}