{"api_version":"1","generated_at":"2026-07-20T14:43:24+00:00","cve":"CVE-2026-64119","urls":{"html":"https://cve.report/CVE-2026-64119","api":"https://cve.report/api/cve/CVE-2026-64119.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-64119","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-64119"},"summary":{"title":"l2tp: use list_del_rcu in l2tp_session_unhash","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nl2tp: use list_del_rcu in l2tp_session_unhash\n\nAn unprivileged local user can pin a host CPU indefinitely in\nl2tp_session_get_by_ifname() by issuing L2TP_CMD_SESSION_GET on\nL2TP_ATTR_IFNAME concurrently with L2TP_CMD_SESSION_CREATE and\nL2TP_CMD_SESSION_DELETE on the same tunnel. All three commands take\nGENL_UNS_ADMIN_PERM, so CAP_NET_ADMIN in the netns user namespace\nsuffices; on any host that has l2tp_core loaded the trigger is\nreachable from a standard `unshare -Urn` sandbox.\n\nl2tp_session_unhash() removes a session from tunnel->session_list\nwith list_del_init(), but that list is walked by\nl2tp_session_get_by_ifname() with list_for_each_entry_rcu() under\nrcu_read_lock_bh(). list_del_init() leaves the deleted entry's\nnext/prev self-pointing; a reader that has loaded the entry and\nthen advances pos->list.next reads &session->list, container_of()s\nback to the same session, and list_for_each_entry_rcu() never\nreaches the list head. The CPU stays in strcmp() inside the\nwalker, with BH and preemption disabled, so RCU grace periods on\nthe host stall behind it and the wedged thread cannot be killed\n(SIGKILL is delivered on syscall return).\n\nUse list_del_rcu() to match the existing list_add_rcu() in\nl2tp_session_register(); the deleted session remains visible to\nin-flight walkers with consistent next/prev pointers until\nkfree_rcu() in l2tp_session_free() releases it. tunnel->session_list\nhas exactly one list_del_init() call site; the list_del_init\n(&session->clist) at l2tp_core.c:533 operates on the per-collision\nlist, which is not walked under RCU. list_empty(&session->list) is\nnot used anywhere in net/l2tp/ after the unhash point, so dropping\nthe post-delete self-init is safe; the fix has no userspace-visible\nbehavior change.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-19 16:17:53","updated_at":"2026-07-19 16:17:53"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/979c017803c40829b03acd9e5236e354b7622360","name":"https://git.kernel.org/stable/c/979c017803c40829b03acd9e5236e354b7622360","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/5e40919a40cb3e590ed45c2a54a4a2518aa88a99","name":"https://git.kernel.org/stable/c/5e40919a40cb3e590ed45c2a54a4a2518aa88a99","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e0c3dd7b30cc5ee42ab502da140cda93d794a20b","name":"https://git.kernel.org/stable/c/e0c3dd7b30cc5ee42ab502da140cda93d794a20b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/acab6314bb75be994f720ed13e9d9139cbf828a8","name":"https://git.kernel.org/stable/c/acab6314bb75be994f720ed13e9d9139cbf828a8","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-64119","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64119","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 89b768ec2dfefaeba5212de14fc71368e12d06ba 5e40919a40cb3e590ed45c2a54a4a2518aa88a99 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 89b768ec2dfefaeba5212de14fc71368e12d06ba e0c3dd7b30cc5ee42ab502da140cda93d794a20b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 89b768ec2dfefaeba5212de14fc71368e12d06ba acab6314bb75be994f720ed13e9d9139cbf828a8 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 89b768ec2dfefaeba5212de14fc71368e12d06ba 979c017803c40829b03acd9e5236e354b7622360 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b3dd82a879f25db9d096ae3053f657aa4260ecc6 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.11.3 6.12 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.12","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.92 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.34 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0.11 7.0.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/l2tp/l2tp_core.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"5e40919a40cb3e590ed45c2a54a4a2518aa88a99","status":"affected","version":"89b768ec2dfefaeba5212de14fc71368e12d06ba","versionType":"git"},{"lessThan":"e0c3dd7b30cc5ee42ab502da140cda93d794a20b","status":"affected","version":"89b768ec2dfefaeba5212de14fc71368e12d06ba","versionType":"git"},{"lessThan":"acab6314bb75be994f720ed13e9d9139cbf828a8","status":"affected","version":"89b768ec2dfefaeba5212de14fc71368e12d06ba","versionType":"git"},{"lessThan":"979c017803c40829b03acd9e5236e354b7622360","status":"affected","version":"89b768ec2dfefaeba5212de14fc71368e12d06ba","versionType":"git"},{"status":"affected","version":"b3dd82a879f25db9d096ae3053f657aa4260ecc6","versionType":"git"},{"lessThan":"6.12","status":"affected","version":"6.11.3","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/l2tp/l2tp_core.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.12"},{"lessThan":"6.12","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.92","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.34","versionType":"semver"},{"lessThanOrEqual":"7.0.*","status":"unaffected","version":"7.0.11","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.92","versionStartIncluding":"6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.34","versionStartIncluding":"6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0.11","versionStartIncluding":"6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1","versionStartIncluding":"6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11.3","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nl2tp: use list_del_rcu in l2tp_session_unhash\n\nAn unprivileged local user can pin a host CPU indefinitely in\nl2tp_session_get_by_ifname() by issuing L2TP_CMD_SESSION_GET on\nL2TP_ATTR_IFNAME concurrently with L2TP_CMD_SESSION_CREATE and\nL2TP_CMD_SESSION_DELETE on the same tunnel. All three commands take\nGENL_UNS_ADMIN_PERM, so CAP_NET_ADMIN in the netns user namespace\nsuffices; on any host that has l2tp_core loaded the trigger is\nreachable from a standard `unshare -Urn` sandbox.\n\nl2tp_session_unhash() removes a session from tunnel->session_list\nwith list_del_init(), but that list is walked by\nl2tp_session_get_by_ifname() with list_for_each_entry_rcu() under\nrcu_read_lock_bh(). list_del_init() leaves the deleted entry's\nnext/prev self-pointing; a reader that has loaded the entry and\nthen advances pos->list.next reads &session->list, container_of()s\nback to the same session, and list_for_each_entry_rcu() never\nreaches the list head. The CPU stays in strcmp() inside the\nwalker, with BH and preemption disabled, so RCU grace periods on\nthe host stall behind it and the wedged thread cannot be killed\n(SIGKILL is delivered on syscall return).\n\nUse list_del_rcu() to match the existing list_add_rcu() in\nl2tp_session_register(); the deleted session remains visible to\nin-flight walkers with consistent next/prev pointers until\nkfree_rcu() in l2tp_session_free() releases it. tunnel->session_list\nhas exactly one list_del_init() call site; the list_del_init\n(&session->clist) at l2tp_core.c:533 operates on the per-collision\nlist, which is not walked under RCU. list_empty(&session->list) is\nnot used anywhere in net/l2tp/ after the unhash point, so dropping\nthe post-delete self-init is safe; the fix has no userspace-visible\nbehavior change."}],"providerMetadata":{"dateUpdated":"2026-07-19T15:40:18.331Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/5e40919a40cb3e590ed45c2a54a4a2518aa88a99"},{"url":"https://git.kernel.org/stable/c/e0c3dd7b30cc5ee42ab502da140cda93d794a20b"},{"url":"https://git.kernel.org/stable/c/acab6314bb75be994f720ed13e9d9139cbf828a8"},{"url":"https://git.kernel.org/stable/c/979c017803c40829b03acd9e5236e354b7622360"}],"title":"l2tp: use list_del_rcu in l2tp_session_unhash","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-64119","datePublished":"2026-07-19T15:40:18.331Z","dateReserved":"2026-07-19T07:54:57.035Z","dateUpdated":"2026-07-19T15:40:18.331Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-19 16:17:53","lastModifiedDate":"2026-07-19 16:17:53","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"64119","Ordinal":"1","Title":"l2tp: use list_del_rcu in l2tp_session_unhash","CVE":"CVE-2026-64119","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"64119","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nl2tp: use list_del_rcu in l2tp_session_unhash\n\nAn unprivileged local user can pin a host CPU indefinitely in\nl2tp_session_get_by_ifname() by issuing L2TP_CMD_SESSION_GET on\nL2TP_ATTR_IFNAME concurrently with L2TP_CMD_SESSION_CREATE and\nL2TP_CMD_SESSION_DELETE on the same tunnel. All three commands take\nGENL_UNS_ADMIN_PERM, so CAP_NET_ADMIN in the netns user namespace\nsuffices; on any host that has l2tp_core loaded the trigger is\nreachable from a standard `unshare -Urn` sandbox.\n\nl2tp_session_unhash() removes a session from tunnel->session_list\nwith list_del_init(), but that list is walked by\nl2tp_session_get_by_ifname() with list_for_each_entry_rcu() under\nrcu_read_lock_bh(). list_del_init() leaves the deleted entry's\nnext/prev self-pointing; a reader that has loaded the entry and\nthen advances pos->list.next reads &session->list, container_of()s\nback to the same session, and list_for_each_entry_rcu() never\nreaches the list head. The CPU stays in strcmp() inside the\nwalker, with BH and preemption disabled, so RCU grace periods on\nthe host stall behind it and the wedged thread cannot be killed\n(SIGKILL is delivered on syscall return).\n\nUse list_del_rcu() to match the existing list_add_rcu() in\nl2tp_session_register(); the deleted session remains visible to\nin-flight walkers with consistent next/prev pointers until\nkfree_rcu() in l2tp_session_free() releases it. tunnel->session_list\nhas exactly one list_del_init() call site; the list_del_init\n(&session->clist) at l2tp_core.c:533 operates on the per-collision\nlist, which is not walked under RCU. list_empty(&session->list) is\nnot used anywhere in net/l2tp/ after the unhash point, so dropping\nthe post-delete self-init is safe; the fix has no userspace-visible\nbehavior change.","Type":"Description","Title":"l2tp: use list_del_rcu in l2tp_session_unhash"}]}}}