{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-43385", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-05-01T14:12:56.006Z", "datePublished": "2026-05-08T14:21:32.007Z", "dateUpdated": "2026-08-05T12:27:43.989Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:27:43.989Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: Fix rcu_tasks stall in threaded busypoll\n\nI was debugging a NIC driver when I noticed that when I enable\nthreaded busypoll, bpftrace hangs when starting up. dmesg showed:\n\n rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 10658 jiffies old.\n rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 40793 jiffies old.\n rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 131273 jiffies old.\n rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 402058 jiffies old.\n INFO: rcu_tasks detected stalls on tasks:\n 00000000769f52cd: .N nvcsw: 2/2 holdout: 1 idle_cpu: -1/64\n task:napi/eth2-8265 state:R running task stack:0 pid:48300 tgid:48300 ppid:2 task_flags:0x208040 flags:0x00004000\n Call Trace:\n \n ? napi_threaded_poll_loop+0x27c/0x2c0\n ? __pfx_napi_threaded_poll+0x10/0x10\n ? napi_threaded_poll+0x26/0x80\n ? kthread+0xfa/0x240\n ? __pfx_kthread+0x10/0x10\n ? ret_from_fork+0x31/0x50\n ? __pfx_kthread+0x10/0x10\n ? ret_from_fork_asm+0x1a/0x30\n \n\nThe cause is that in threaded busypoll, the main loop is in\nnapi_threaded_poll rather than napi_threaded_poll_loop, where the\nlatter rarely iterates more than once within its loop. For\nrcu_softirq_qs_periodic inside napi_threaded_poll_loop to report its\nqs state, the last_qs must be 100ms behind, and this can't happen\nbecause napi_threaded_poll_loop rarely iterates in threaded busypoll,\nand each time napi_threaded_poll_loop is called last_qs is reset to\nlatest jiffies.\n\nThis patch changes so that in threaded busypoll, last_qs is saved\nin the outer napi_threaded_poll, and whether busy_poll_last_qs\nis NULL indicates whether napi_threaded_poll_loop is called for\nbusypoll. This way last_qs would not reset to latest jiffies on\neach invocation of napi_threaded_poll_loop." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - In a reasonable high-impact deployment, threaded NAPI busy-poll is enabled on a network-facing NIC/forwarder, and received packets schedule the NAPI kthread into the vulnerable polling loop. The netlink knob is an administrative deployment gate, but a remote sender needs no local access once that mode is in use.\nAC:L - There is no attacker-controlled race or fragile timing requirement; once the NAPI thread is in threaded busy-poll mode, repeated loop invocations reliably fail to report RCU Tasks quiescent states. Packet delivery to the configured NAPI is sufficient to activate the path.\nPR:N - The highest-impact scenario is an already-configured network service/device where the attacker only sends packets and needs no account or credentials. Enabling threaded busy-poll itself requires init-namespace CAP_NET_ADMIN, but that is a deployment precondition rather than an exploit privilege in this scenario.\nUI:N - No victim user action is required after the affected NAPI mode is configured. Network traffic alone can keep the vulnerable kthread path active.\nS:U - The impact remains within the kernel and host networking/RCU scheduling authority. There is no VM escape, sandbox boundary crossing, or separate security authority affected.\nC:N - The bug is an RCU Tasks quiescent-state starvation/stall, not memory corruption or an information disclosure path. I found no read primitive or exposure of protected data.\nI:N - The flaw does not provide an arbitrary write, control-flow hijack, or data modification primitive. It only prevents timely RCU Tasks grace-period progress.\nA:H - The vulnerable loop can indefinitely stall RCU Tasks grace periods, causing kernel operations such as tracing/BPF setup or teardown to hang and producing persistent RCU stall reports. This is a kernel-level hang/deadlock-style availability failure." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/core/dev.c" ], "versions": [ { "version": "c18d4b190a46651726c9a952667c74d2deb33c28", "lessThan": "52459201d0df3fdbb1d281738b7b772e2cacb49c", "status": "affected", "versionType": "git" }, { "version": "c18d4b190a46651726c9a952667c74d2deb33c28", "lessThan": "1a86a1f7d88996085934139fa4c063b6299a2dd3", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/core/dev.c" ], "versions": [ { "version": "6.19", "status": "affected" }, { "version": "0", "lessThan": "6.19", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.9", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "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": "6.19", "versionEndExcluding": "6.19.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/52459201d0df3fdbb1d281738b7b772e2cacb49c" }, { "url": "https://git.kernel.org/stable/c/1a86a1f7d88996085934139fa4c063b6299a2dd3" } ], "title": "net: Fix rcu_tasks stall in threaded busypoll", "x_generator": { "engine": "bippy-1.2.0" } } } }