{"api_version":"1","generated_at":"2026-08-16T06:01:31+00:00","cve":"CVE-2026-74543","urls":{"html":"https://cve.report/CVE-2026-74543","api":"https://cve.report/api/cve/CVE-2026-74543.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-74543","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-74543"},"summary":{"title":"net: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()\n\nsyzbot reported a memory leak [1] in the UDP tunnel NIC offload code.\n\nWhen device registration fails (e.g. in register_netdevice()), netdev core\nunwinds by sending a single NETDEV_UNREGISTER notification. If work was queued\nduring NETDEV_REGISTER (utn->work_pending is set), udp_tunnel_nic_unregister()\nreturns early:\n\n\tif (utn->work_pending)\n\t\treturn;\n\nBecause failed registrations do not enter netdev_wait_allrefs_any(), no\nsubsequent NETDEV_UNREGISTER rebroadcast will ever occur. As a result, the\nstruct udp_tunnel_nic allocated in udp_tunnel_nic_alloc() is leaked\npermanently.\n\nFix this by removing the early return. Instead, synchronously cancel any\npending work with cancel_delayed_work_sync() before freeing @utn.\n\nTo be able to call cancel_delayed_work_sync() while holding RTNL (the work also\nneeds RTNL), switch udp_tunnel_nic_device_sync_work() to rtnl_trylock(). If RTNL\nis contended, requeue the work with a 1 jiffy delay (via queue_delayed_work())\nto prevent high CPU contention while waiting for RTNL lock.\n\nThe utn->work_pending bookkeeping is no longer needed and is removed, as\nthe workqueue core already tracks the pending/running state of the work.\n\n[1]\nBUG: memory leak\nunreferenced object 0xffff888127d5f840 (size 96):\n  comm \"syz-executor\", pid 5806, jiffies 4294942188\n  backtrace (crc 99fdb6c8):\n    __kmalloc_noprof+0x3bf/0x550\n    udp_tunnel_nic_alloc net/ipv4/udp_tunnel_nic.c:756 [inline]\n    udp_tunnel_nic_register net/ipv4/udp_tunnel_nic.c:833 [inline]\n    udp_tunnel_nic_netdevice_event+0x804/0xab0 net/ipv4/udp_tunnel_nic.c:931\n    notifier_call_chain+0x59/0x160 kernel/notifier.c:85\n    call_netdevice_notifiers_info+0x7d/0xb0 net/core/dev.c:2250\n    register_netdevice+0xc10/0xeb0 net/core/dev.c:11478","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 13:17:59","updated_at":"2026-08-15 13:17:59"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/080695e6f005e2396f1207fd69d24c442cb230c6","name":"https://git.kernel.org/stable/c/080695e6f005e2396f1207fd69d24c442cb230c6","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b712da45bd9b9835d132e9fbc0c3e43c164cb1fd","name":"https://git.kernel.org/stable/c/b712da45bd9b9835d132e9fbc0c3e43c164cb1fd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b322532a4b774db1b480a2de84125910a70739a5","name":"https://git.kernel.org/stable/c/b322532a4b774db1b480a2de84125910a70739a5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f82a2ded3d7a9098267c84f14eafdb98c4550ac5","name":"https://git.kernel.org/stable/c/f82a2ded3d7a9098267c84f14eafdb98c4550ac5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-74543","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74543","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected cc4e3835eff474aa274d6e1d18f69d9d296d3b76 b712da45bd9b9835d132e9fbc0c3e43c164cb1fd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected cc4e3835eff474aa274d6e1d18f69d9d296d3b76 f82a2ded3d7a9098267c84f14eafdb98c4550ac5 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected cc4e3835eff474aa274d6e1d18f69d9d296d3b76 b322532a4b774db1b480a2de84125910a70739a5 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected cc4e3835eff474aa274d6e1d18f69d9d296d3b76 080695e6f005e2396f1207fd69d24c442cb230c6 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.9","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.9 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.103 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.44 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.8 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2-rc6 * 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/ipv4/udp_tunnel_nic.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"b712da45bd9b9835d132e9fbc0c3e43c164cb1fd","status":"affected","version":"cc4e3835eff474aa274d6e1d18f69d9d296d3b76","versionType":"git"},{"lessThan":"f82a2ded3d7a9098267c84f14eafdb98c4550ac5","status":"affected","version":"cc4e3835eff474aa274d6e1d18f69d9d296d3b76","versionType":"git"},{"lessThan":"b322532a4b774db1b480a2de84125910a70739a5","status":"affected","version":"cc4e3835eff474aa274d6e1d18f69d9d296d3b76","versionType":"git"},{"lessThan":"080695e6f005e2396f1207fd69d24c442cb230c6","status":"affected","version":"cc4e3835eff474aa274d6e1d18f69d9d296d3b76","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/ipv4/udp_tunnel_nic.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.9"},{"lessThan":"5.9","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.103","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.44","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.8","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2-rc6","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.103","versionStartIncluding":"5.9","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.44","versionStartIncluding":"5.9","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.8","versionStartIncluding":"5.9","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2-rc6","versionStartIncluding":"5.9","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()\n\nsyzbot reported a memory leak [1] in the UDP tunnel NIC offload code.\n\nWhen device registration fails (e.g. in register_netdevice()), netdev core\nunwinds by sending a single NETDEV_UNREGISTER notification. If work was queued\nduring NETDEV_REGISTER (utn->work_pending is set), udp_tunnel_nic_unregister()\nreturns early:\n\n\tif (utn->work_pending)\n\t\treturn;\n\nBecause failed registrations do not enter netdev_wait_allrefs_any(), no\nsubsequent NETDEV_UNREGISTER rebroadcast will ever occur. As a result, the\nstruct udp_tunnel_nic allocated in udp_tunnel_nic_alloc() is leaked\npermanently.\n\nFix this by removing the early return. Instead, synchronously cancel any\npending work with cancel_delayed_work_sync() before freeing @utn.\n\nTo be able to call cancel_delayed_work_sync() while holding RTNL (the work also\nneeds RTNL), switch udp_tunnel_nic_device_sync_work() to rtnl_trylock(). If RTNL\nis contended, requeue the work with a 1 jiffy delay (via queue_delayed_work())\nto prevent high CPU contention while waiting for RTNL lock.\n\nThe utn->work_pending bookkeeping is no longer needed and is removed, as\nthe workqueue core already tracks the pending/running state of the work.\n\n[1]\nBUG: memory leak\nunreferenced object 0xffff888127d5f840 (size 96):\n  comm \"syz-executor\", pid 5806, jiffies 4294942188\n  backtrace (crc 99fdb6c8):\n    __kmalloc_noprof+0x3bf/0x550\n    udp_tunnel_nic_alloc net/ipv4/udp_tunnel_nic.c:756 [inline]\n    udp_tunnel_nic_register net/ipv4/udp_tunnel_nic.c:833 [inline]\n    udp_tunnel_nic_netdevice_event+0x804/0xab0 net/ipv4/udp_tunnel_nic.c:931\n    notifier_call_chain+0x59/0x160 kernel/notifier.c:85\n    call_netdevice_notifiers_info+0x7d/0xb0 net/core/dev.c:2250\n    register_netdevice+0xc10/0xeb0 net/core/dev.c:11478"}],"providerMetadata":{"dateUpdated":"2026-08-15T12:27:53.336Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/b712da45bd9b9835d132e9fbc0c3e43c164cb1fd"},{"url":"https://git.kernel.org/stable/c/f82a2ded3d7a9098267c84f14eafdb98c4550ac5"},{"url":"https://git.kernel.org/stable/c/b322532a4b774db1b480a2de84125910a70739a5"},{"url":"https://git.kernel.org/stable/c/080695e6f005e2396f1207fd69d24c442cb230c6"}],"title":"net: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-74543","datePublished":"2026-08-15T12:27:53.336Z","dateReserved":"2026-08-15T05:44:03.914Z","dateUpdated":"2026-08-15T12:27:53.336Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 13:17:59","lastModifiedDate":"2026-08-15 13:17:59","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"74543","Ordinal":"1","Title":"net: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()","CVE":"CVE-2026-74543","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"74543","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()\n\nsyzbot reported a memory leak [1] in the UDP tunnel NIC offload code.\n\nWhen device registration fails (e.g. in register_netdevice()), netdev core\nunwinds by sending a single NETDEV_UNREGISTER notification. If work was queued\nduring NETDEV_REGISTER (utn->work_pending is set), udp_tunnel_nic_unregister()\nreturns early:\n\n\tif (utn->work_pending)\n\t\treturn;\n\nBecause failed registrations do not enter netdev_wait_allrefs_any(), no\nsubsequent NETDEV_UNREGISTER rebroadcast will ever occur. As a result, the\nstruct udp_tunnel_nic allocated in udp_tunnel_nic_alloc() is leaked\npermanently.\n\nFix this by removing the early return. Instead, synchronously cancel any\npending work with cancel_delayed_work_sync() before freeing @utn.\n\nTo be able to call cancel_delayed_work_sync() while holding RTNL (the work also\nneeds RTNL), switch udp_tunnel_nic_device_sync_work() to rtnl_trylock(). If RTNL\nis contended, requeue the work with a 1 jiffy delay (via queue_delayed_work())\nto prevent high CPU contention while waiting for RTNL lock.\n\nThe utn->work_pending bookkeeping is no longer needed and is removed, as\nthe workqueue core already tracks the pending/running state of the work.\n\n[1]\nBUG: memory leak\nunreferenced object 0xffff888127d5f840 (size 96):\n  comm \"syz-executor\", pid 5806, jiffies 4294942188\n  backtrace (crc 99fdb6c8):\n    __kmalloc_noprof+0x3bf/0x550\n    udp_tunnel_nic_alloc net/ipv4/udp_tunnel_nic.c:756 [inline]\n    udp_tunnel_nic_register net/ipv4/udp_tunnel_nic.c:833 [inline]\n    udp_tunnel_nic_netdevice_event+0x804/0xab0 net/ipv4/udp_tunnel_nic.c:931\n    notifier_call_chain+0x59/0x160 kernel/notifier.c:85\n    call_netdevice_notifiers_info+0x7d/0xb0 net/core/dev.c:2250\n    register_netdevice+0xc10/0xeb0 net/core/dev.c:11478","Type":"Description","Title":"net: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()"}]}}}