CVE-2025-21926

{"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": "2026-11-10T12:35:32.202Z"}, "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 \u2014 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 \u2014 datapath and flow setup, then a single sendmsg \u2014 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 \u2014 `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` \u2014 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": 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"cpe:2.3:o:linux:linux_kernel:6.14:rc4:*:*:*:*:*:*", "matchCriteriaId": "D3D6550E-6679-4560-902D-AF52DCFE905B", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.14:rc5:*:*:*:*:*:*", "matchCriteriaId": "45B90F6B-BEC7-4D4E-883A-9DBADE021750", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "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."}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net: gso: correcci\u00f3n de propiedad en __udp_gso_segment. En __udp_gso_segment, el destructor de skb se elimina antes de segmentar el skb, pero la referencia del socket se mantiene intacta. Esto supone un problema si el skb original queda hu\u00e9rfano posteriormente, ya que podemos encontrarnos con el siguiente error: \u00a1ERROR del kernel en ./include/linux/skbuff.h:3312! (skb_orphan) RIP: 0010:ip_rcv_core+0x8b2/0xca0 Rastreo de llamadas: ip_rcv+0xab/0x6e0 __netif_receive_skb_one_core+0x168/0x1b0 process_backlog+0x384/0x1100 __napi_poll.constprop.0+0xa1/0x370 net_rx_action+0x925/0xe50 Lo anterior puede suceder despu\u00e9s de una secuencia de eventos al usar OpenVSwitch, cuando una acci\u00f3n OVS_ACTION_ATTR_USERSPACE precede a una acci\u00f3n OVS_ACTION_ATTR_OUTPUT: 1. Se maneja OVS_ACTION_ATTR_USERSPACE (en do_execute_actions): el skb pasa por queue_gso_packets y luego __udp_gso_segment, donde se elimina su destructor. 2. Los datos de los segmentos se copian y se env\u00edan al espacio de usuario. 3. Se gestiona OVS_ACTION_ATTR_OUTPUT (en do_execute_actions) y se env\u00eda el mismo skb original a su ruta. 4. Si posteriormente se encuentra con skb_orphan, se detecta el error. Para solucionarlo, elimine tambi\u00e9n la referencia al socket en __udp_gso_segment."}], "id": "CVE-2025-21926", "lastModified": "2026-11-10T13:17:39.567", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 5.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2025-04-01T16:15:23.350", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/01a83237644d6822bc7df2c5564fc81b0df84358"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/084819b0d8b1bd433b90142371eb9450d657f8ca"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/455217ac9db0cf9349b3933664355e907bb1a569"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/9f28205ddb76e86cac418332e952241d85fed0dc"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/a2d1cca955ed34873e524cc2e6e885450d262f05"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/c32da44cc9298eaa6109e3fc2c2b4e07cc4bf11b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/e8db70537878e1bb3fd83e5abcc6feefc0587828"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/ee01b2f2d7d0010787c2343463965bbc283a497f"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"}, {"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"}, {"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "url": "https://cert-portal.siemens.com/productcert/html/ssa-457936.html"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "NVD-CWE-noinfo"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"affected_release": [{"advisory": "RHSA-2025:8669", "cpe": "cpe:/o:redhat:enterprise_linux:10.0", "package": "kernel-0:6.12.0-55.16.1.el10_0", "product_name": "Red Hat Enterprise Linux 10", "release_date": "2025-06-09T00:00:00Z"}, {"advisory": "RHSA-2025:8643", "cpe": "cpe:/a:redhat:enterprise_linux:9", "package": "kernel-0:5.14.0-570.21.1.el9_6", "product_name": "Red Hat Enterprise Linux 9", "release_date": "2025-06-09T00:00:00Z"}, {"advisory": "RHSA-2025:8643", "cpe": "cpe:/o:redhat:enterprise_linux:9", "package": "kernel-0:5.14.0-570.21.1.el9_6", "product_name": "Red Hat Enterprise Linux 9", "release_date": "2025-06-09T00:00:00Z"}], "bugzilla": {"description": "kernel: net: gso: fix ownership in __udp_gso_segment", "id": "2356587", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2356587"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "verified"}, "cwe": "CWE-416", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nnet: gso: fix ownership in __udp_gso_segment\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:\nkernel BUG at ./include/linux/skbuff.h:3312! (skb_orphan)\nRIP: 0010:ip_rcv_core+0x8b2/0xca0\nCall Trace:\nip_rcv+0xab/0x6e0\n__netif_receive_skb_one_core+0x168/0x1b0\nprocess_backlog+0x384/0x1100\n__napi_poll.constprop.0+0xa1/0x370\nnet_rx_action+0x925/0xe50\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:\n1. OVS_ACTION_ATTR_USERSPACE is handled (in do_execute_actions): the skb\ngoes through queue_gso_packets and then __udp_gso_segment, where its\ndestructor 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\nsame original skb is sent to its path.\n4. If it later hits skb_orphan, we hit the bug.\nFix this by also removing the reference to the socket in\n__udp_gso_segment."], "mitigation": {"lang": "en:us", "value": "Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability."}, "name": "CVE-2025-21926", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2025-04-01T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-21926\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-21926\nhttps://lore.kernel.org/linux-cve-announce/2025040132-CVE-2025-21926-fd40@gregkh/T"], "statement": "If UDP fragmentation offload being used (that allows a device to fragment an oversized UDP datagram into multiple IPv fragments), then this bug could happen. The bug happens when skb_orphan function later being called. It is complex to trigger the bug (few conditions should happen simultaneously) and only local user can trigger it.", "threat_severity": "Moderate"}

{}