{"id":"CVE-2026-89487","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-89487","summary":"openvswitch: only skb_tx_error() a packet we are about to drop","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nopenvswitch: only skb_tx_error() a packet we are about to drop\n\nqueue_userspace_packet() borrows the packet skb -- it only copies it into\na private netlink message (user_skb) and does not own it; on return\ndo_execute_actions() keeps forwarding it through the flow's remaining\nactions. Its error path nevertheless calls skb_tx_error(skb), which via\nskb_zcopy_clear() does skb_shinfo(skb)->flags &= ~SKBFL_ALL_ZEROCOPY,\nstripping SKBFL_SHARED_FRAG from that live skb (skb_tx_error()'s kerneldoc\nsays \"skb must be freed afterwards\").\n\nFor a MSG_ZEROCOPY skb carrying page-cache frags, SKBFL_SHARED_FRAG is\nwhat makes esp_input() skb_cow_data() before in-place AEAD; once it is\nstripped a later local ESP-in-UDP delivery decrypts in place over pages\nthe sender does not own -- an unprivileged page-cache write (the\n\"Fragnesia\" primitive).\ndo_execute_actions() ignores output_userspace()'s return value, so any\naction after a failed USERSPACE upcall inherits the stripped skb.\n\nMove the skb_tx_error() to the flow-miss drop path - the \"default\"\nbranch of ovs_dp_process_packet()'s switch(error), before kfree_skb().\n\nThe call has been here since commit 36d5fe6a0007 (\"core, nfqueue,\nopenvswitch: Orphan frags in skb_zerocopy and handle errors\") but was\nharmless until esp_input() began relying on SKBFL_SHARED_FRAG to gate\nin-place decrypt; only then did stripping it on a still-forwarded skb\nbecome a page-cache write primitive.","published":"2026-09-11T19:43:40.776Z","modified":"2026-09-14T03:46:05.345520997Z","cvss":{"score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.12.109"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0dbc2398fca3bb33eda963849f865ddb1b3aa05e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5d85eef222cfd28e73deed7402c100229e8b9e6e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6767d70cf46f65807a6a4c4406a518e6c12e36ae"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e41a59fc056f63a7a1f42788913c53cc48d744aa"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89487.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89487"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-14T03:46:05.345520997Z"}}