{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74727", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.929Z", "datePublished": "2026-08-22T15:33:17.773Z", "dateUpdated": "2026-08-25T05:42:08.380Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-25T05:42:08.380Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\novpn: skip rehash for peers already removed from by_id\n\novpn_nl_peer_set_doit() resolves the target peer via\novpn_peer_get_by_id() before taking ovpn->lock. In the window between\nthe lookup (which only takes a refcount) and the subsequent\nspin_lock_bh(&ovpn->lock), a concurrent OVPN_CMD_PEER_DEL, keepalive\nexpiry, or socket teardown can take ovpn->lock first, run\novpn_peer_remove() to unhash the peer from all four tables (by_id,\nby_vpn_addr4/6, by_transp_addr) and release the lock. set_doit then\nacquires ovpn->lock and calls ovpn_peer_hash_vpn_ip(), which\nre-inserts the now-removed peer back into the rehashing tables.\n\nThe same race affects the float path: ovpn_peer_endpoints_update()\nholds only a refcount and acquires ovpn->lock very late (after async\nAEAD decrypt and a netlink notification), then rehashes the peer\nin the by_transp_addr table.\n\nThe resurrected peer becomes reachable again from the RX lookup\n(ovpn_peer_get_by_transp_addr) and the TX VPN-IP lookup, even though\nuserspace believes it is gone. Once the data-path refcount drops the\npeer is freed via call_rcu while the hash entries embedded in it\nremain linked, opening a UAF window.\n\nBail out of the rehash when hash_entry_id is unhashed, mirroring\nthe sentinel already used by ovpn_peer_remove() to detect the\nalready-removed state. The check is safe under ovpn->lock, which\nserializes every mutation of hash_entry_id, and is a no-op for the\nadd path because ovpn_peer_add_mp() inserts hash_entry_id before\ncalling ovpn_peer_hash_vpn_ip()." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The float-path UAF is reached from ovpn_udp_encap_recv()/ovpn_tcp_rcv() through ovpn_recv(), async AEAD decrypt, and ovpn_peer_endpoints_update(); a remote peer sends authenticated DATA_V2 packets over UDP/TCP to an internet-facing MP-mode OpenVPN gateway.\nAC:L - The remote peer controls float timing (new transport source), packet rate, and concurrent removal via TCP disconnect, UDP socket teardown, or keepalive expiry; netlink PEER_SET vs PEER_DEL races are likewise attacker-synchronized with no luck-dependent layout.\nPR:N - On an internet-facing MP-mode gateway, exploitation needs no Linux credentials on the victim—only an established kernel-installed peer with valid AEAD keys (or namespace CAP_NET_ADMIN for netlink races), matching a remote VPN client rather than host root.\nUI:N - The rehash race is triggered by normal peer traffic and automatic keepalive/socket teardown; no administrator or end-user action on the victim host is required beyond routine VPN server operation.\nS:U - The UAF corrupts ovpn peer hash tables inside the kernel VPN driver; impact remains within the host kernel security domain without crossing VM, container, or IOMMU boundaries.\nC:H - Freed ovpn_peer objects remain linked in by_transp_addr/by_vpn_addr hash tables, so RX/TX lookups dereference recycled kmalloc-1k structures and enable arbitrary kernel-memory reads via attacker-controlled heap reuse.\nI:H - Resurrected hash entries steer traffic to freed peers and subsequent RCU/kref teardown on stale objects provide typical slab-UAF write primitives (refcount, socket, crypto pointer updates) suitable for kernel code execution.\nA:H - Use-after-free on hot datapath peer lookups reliably causes kernel oops/panic or slab corruption on VPN gateways, and remote peers can repeat the race to sustain denial of service." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ovpn/peer.c" ], "versions": [ { "version": "1d36a36f6d5347360ef9681a05f6166683bafd1d", "lessThan": "d20c181088984b6eaa8d7fe7cb5ab3510988df59", "status": "affected", "versionType": "git" }, { "version": "1d36a36f6d5347360ef9681a05f6166683bafd1d", "lessThan": "66745480298775f188b2f5ad266643e85a90f73b", "status": "affected", "versionType": "git" }, { "version": "1d36a36f6d5347360ef9681a05f6166683bafd1d", "lessThan": "33ec10567fe14456063daf549fdf1a4f53448e4c", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ovpn/peer.c" ], "versions": [ { "version": "6.16", "status": "affected" }, { "version": "0", "lessThan": "6.16", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.45", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.9", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "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": "6.16", "versionEndExcluding": "6.18.45" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.16", "versionEndExcluding": "7.1.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.16", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/d20c181088984b6eaa8d7fe7cb5ab3510988df59" }, { "url": "https://git.kernel.org/stable/c/66745480298775f188b2f5ad266643e85a90f73b" }, { "url": "https://git.kernel.org/stable/c/33ec10567fe14456063daf549fdf1a4f53448e4c" } ], "title": "ovpn: skip rehash for peers already removed from by_id", "x_generator": { "engine": "bippy-1.2.0" } } } }