{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-21926", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-29T08:45:45.788Z", "datePublished": "2025-04-01T15:40:57.882Z", "dateUpdated": "2026-08-05T11:55:23.999Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:55:23.999Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: gso: fix ownership in __udp_gso_segment\n\nIn __udp_gso_segment the skb destructor is removed before segmenting the\nskb but the socket reference is kept as-is. This is an issue if the\noriginal skb is later orphaned as we can hit the following bug:\n\n kernel BUG at ./include/linux/skbuff.h:3312! (skb_orphan)\n RIP: 0010:ip_rcv_core+0x8b2/0xca0\n Call Trace:\n ip_rcv+0xab/0x6e0\n __netif_receive_skb_one_core+0x168/0x1b0\n process_backlog+0x384/0x1100\n __napi_poll.constprop.0+0xa1/0x370\n net_rx_action+0x925/0xe50\n\nThe above can happen following a sequence of events when using\nOpenVSwitch, when an OVS_ACTION_ATTR_USERSPACE action precedes an\nOVS_ACTION_ATTR_OUTPUT action:\n\n1. OVS_ACTION_ATTR_USERSPACE is handled (in do_execute_actions): the skb\n goes through queue_gso_packets and then __udp_gso_segment, where its\n destructor is removed.\n2. The segments' data are copied and sent to userspace.\n3. OVS_ACTION_ATTR_OUTPUT is handled (in do_execute_actions) and the\n same original skb is sent to its path.\n4. If it later hits skb_orphan, we hit the bug.\n\nFix this by also removing the reference to the socket in\n__udp_gso_segment." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug only fires on a locally originated UDP GSO skb that still carries a socket owner (`copy_dtor` requires `destructor == sock_wfree`); forwarded/remote packets are already orphaned with `sk == NULL`. The attacker must therefore have a local account to open the UDP socket and to program the OVS datapath.\nAC:L - The trigger is fully deterministic — install a flow whose actions are userspace-then-output, then `sendmsg()` one `UDP_SEGMENT` packet larger than gso_size, and `BUG_ON(skb->sk)` fires every time with no race to win or memory layout to guess. The socket-free window for the use-after-free variant is likewise attacker-controlled on both sides (send, then `close()` while the skb is still queued).\nPR:L - An unprivileged user suffices: every OVS generic-netlink op uses GENL_UNS_ADMIN_PERM with `.netnsok = true`, so `unshare -Urn` grants the required CAP_NET_ADMIN in the new user/net namespace, and `ctrl_getfamily()` autoloads openvswitch.ko with no capability check. On real OVN/OpenStack hosts no attacker setup is needed at all, since sFlow/IPFIX sampling and controller-style rules already emit userspace+output action lists.\nUI:N - The attacker performs the entire sequence — datapath and flow setup, then a single sendmsg — from its own process. No administrator or victim action is involved.\nS:U - The corruption and the crash both occur inside the kernel's own security authority; no hypervisor, IOMMU, or sandbox boundary is crossed. This is standard in-kernel impact, so scope is unchanged.\nC:H - The retained skb keeps a `struct sock *` for which the wmem charge was handed to the segments, so once the socket is closed and freed the dangling pointer is dereferenced on the output path — `fq_classify()` reads `sk->sk_state`/`sk->sk_hash` and caches the freed pointer in its flow rbtree, and `netdev_core_pick_tx`/`skb_update_prio`/AF_PACKET taps read it too. A use-after-free on a sprayable slab object gives an attacker-observable read of reclaimed kernel memory.\nI:H - The same dangling `sk` is written through, not just read: `fq_classify()` does `smp_store_release(&sk->sk_pacing_status, SK_PACING_FQ)` and updates `f->socket_hash` from freed memory, so a heap-sprayed replacement object is modified at a known offset. Per the UAF guidance this is an exploitable write primitive against kernel state.\nA:H - `skb_orphan()` in `ip_rcv_core()` hits `BUG_ON(skb->sk)` from `process_backlog`/`net_rx_action` — a BUG in softirq context is a fatal exception in interrupt, i.e. an immediate kernel panic, exactly as shown in the commit's trace. It is repeatable at will with a single packet per attempt." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv4/udp_offload.c" ], "versions": [ { "version": "ad405857b174ed31a97982bb129c320d03321cf5", "lessThan": "9f28205ddb76e86cac418332e952241d85fed0dc", "status": "affected", "versionType": "git" }, { "version": "ad405857b174ed31a97982bb129c320d03321cf5", "lessThan": "a2d1cca955ed34873e524cc2e6e885450d262f05", "status": "affected", "versionType": "git" }, { "version": "ad405857b174ed31a97982bb129c320d03321cf5", "lessThan": "455217ac9db0cf9349b3933664355e907bb1a569", "status": "affected", "versionType": "git" }, { "version": "ad405857b174ed31a97982bb129c320d03321cf5", "lessThan": "e8db70537878e1bb3fd83e5abcc6feefc0587828", "status": "affected", "versionType": "git" }, { "version": "ad405857b174ed31a97982bb129c320d03321cf5", "lessThan": "01a83237644d6822bc7df2c5564fc81b0df84358", "status": "affected", "versionType": "git" }, { "version": "ad405857b174ed31a97982bb129c320d03321cf5", "lessThan": "084819b0d8b1bd433b90142371eb9450d657f8ca", "status": "affected", "versionType": "git" }, { "version": "ad405857b174ed31a97982bb129c320d03321cf5", "lessThan": "c32da44cc9298eaa6109e3fc2c2b4e07cc4bf11b", "status": "affected", "versionType": "git" }, { "version": "ad405857b174ed31a97982bb129c320d03321cf5", "lessThan": "ee01b2f2d7d0010787c2343463965bbc283a497f", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv4/udp_offload.c" ], "versions": [ { "version": "4.18", "status": "affected" }, { "version": "0", "lessThan": "4.18", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.291", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.235", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.179", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.131", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.83", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.19", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13.7", "lessThanOrEqual": "6.13.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.14", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "5.4.291" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "5.10.235" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "5.15.179" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "6.1.131" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "6.6.83" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "6.12.19" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "6.13.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "6.14" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/9f28205ddb76e86cac418332e952241d85fed0dc" }, { "url": "https://git.kernel.org/stable/c/a2d1cca955ed34873e524cc2e6e885450d262f05" }, { "url": "https://git.kernel.org/stable/c/455217ac9db0cf9349b3933664355e907bb1a569" }, { "url": "https://git.kernel.org/stable/c/e8db70537878e1bb3fd83e5abcc6feefc0587828" }, { "url": "https://git.kernel.org/stable/c/01a83237644d6822bc7df2c5564fc81b0df84358" }, { "url": "https://git.kernel.org/stable/c/084819b0d8b1bd433b90142371eb9450d657f8ca" }, { "url": "https://git.kernel.org/stable/c/c32da44cc9298eaa6109e3fc2c2b4e07cc4bf11b" }, { "url": "https://git.kernel.org/stable/c/ee01b2f2d7d0010787c2343463965bbc283a497f" } ], "title": "net: gso: fix ownership in __udp_gso_segment", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html" }, { "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T19:39:23.706Z" } }, { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-07-14T12:40:32.718Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" } ], "references": [ { "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html" } ] } ] } }