{"cve":"CVE-2026-64044","nvd":{"published":"2026-07-19T16:17:44.690","modified":"2026-09-02T21:11:32.317","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\novpn: respect peer refcount in CMD_NEW_PEER error path\n\novpn_nl_peer_new_doit()'s error path calls ovpn_peer_release() directly\nrather than ovpn_peer_put(), bypassing the kref. The accompanying\ncomment (\"peer was not yet hashed, thus it is not used in any context\")\nholds for UDP but not for TCP.\n\nFor UDP, the ovpn_socket union uses the .ovpn arm and never points back\nat a peer; UDP encap_recv looks up peers via the not-yet-populated\nhashtables, so the new peer is unreachable until ovpn_peer_add()\npublishes it.\n\nFor TCP, ovpn_socket_new() sets ovpn_sock->peer and\novpn_tcp_socket_attach() publishes ovpn_sock via rcu_assign_sk_user_data().\nFrom that moment until ovpn_socket_release() detaches in the error path,\nthe TCP fd is fully wired: userspace recvmsg / sendmsg / close / poll\non the fd, as well as the strparser-driven ovpn_tcp_rcv() path, can\nreach the peer through sk_user_data -> ovpn_sock->peer and bump its\nrefcount via ovpn_peer_hold().\n\novpn_tcp_socket_wait_finish() (called inside ovpn_socket_release())\ndrains strparser and the tx work, but does not synchronize with\nuserspace syscall callers that already hold a peer reference. If\novpn_nl_peer_modify() or ovpn_peer_add() returns an error while such\na caller is in flight - notably an ovpn_tcp_recvmsg() blocked in\n__skb_recv_datagram() on peer->tcp.user_queue - the direct\novpn_peer_release() destroys the peer while the caller still holds\nthe reference, and the eventual ovpn_peer_put() from that caller\noperates on freed memory.\n\nReplace the direct destructor call with ovpn_peer_put() so the kref\ncorrectly defers destruction until the last reference is dropped.\nIn the common case where no concurrent user is present, behaviour is\nunchanged: the kref hits zero immediately and ovpn_peer_release_kref()\nruns the same destructor.\n\nWith this conversion ovpn_peer_release() has no callers outside peer.c\n- ovpn_peer_release_kref() in the same translation unit is the only\nremaining user - so make it static and drop its declaration from\npeer.h.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":[],"references":["https://git.kernel.org/stable/c/0c3ef71879c0264de6c42463031d9e057da87840","https://git.kernel.org/stable/c/1fef6614673ff0846d30acdeeaf3cf98bb5f6116","https://git.kernel.org/stable/c/8298834912d76dbc82c12b6b4ab7590ed2bb8ae5"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:45:36.895656543+00:00"},"epss":{"cve":"CVE-2026-64044","score":0.00184,"percentile":0.07984,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}