{"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 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