{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-23340", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-01-13T15:37:45.998Z", "datePublished": "2026-03-25T10:27:28.728Z", "dateUpdated": "2026-08-05T12:21:14.647Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:21:14.647Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: sched: avoid qdisc_reset_all_tx_gt() vs dequeue race for lockless qdiscs\n\nWhen shrinking the number of real tx queues,\nnetif_set_real_num_tx_queues() calls qdisc_reset_all_tx_gt() to flush\nqdiscs for queues which will no longer be used.\n\nqdisc_reset_all_tx_gt() currently serializes qdisc_reset() with\nqdisc_lock(). However, for lockless qdiscs, the dequeue path is\nserialized by qdisc_run_begin/end() using qdisc->seqlock instead, so\nqdisc_reset() can run concurrently with __qdisc_run() and free skbs\nwhile they are still being dequeued, leading to UAF.\n\nThis can easily be reproduced on e.g. virtio-net by imposing heavy\ntraffic while frequently changing the number of queue pairs:\n\n iperf3 -ub0 -c $peer -t 0 &\n while :; do\n ethtool -L eth0 combined 1\n ethtool -L eth0 combined 2\n done\n\nWith KASAN enabled, this leads to reports like:\n\n BUG: KASAN: slab-use-after-free in __qdisc_run+0x133f/0x1760\n ...\n Call Trace:\n \n ...\n __qdisc_run+0x133f/0x1760\n __dev_queue_xmit+0x248f/0x3550\n ip_finish_output2+0xa42/0x2110\n ip_output+0x1a7/0x410\n ip_send_skb+0x2e6/0x480\n udp_send_skb+0xb0a/0x1590\n udp_sendmsg+0x13c9/0x1fc0\n ...\n \n\n Allocated by task 1270 on cpu 5 at 44.558414s:\n ...\n alloc_skb_with_frags+0x84/0x7c0\n sock_alloc_send_pskb+0x69a/0x830\n __ip_append_data+0x1b86/0x48c0\n ip_make_skb+0x1e8/0x2b0\n udp_sendmsg+0x13a6/0x1fc0\n ...\n\n Freed by task 1306 on cpu 3 at 44.558445s:\n ...\n kmem_cache_free+0x117/0x5e0\n pfifo_fast_reset+0x14d/0x580\n qdisc_reset+0x9e/0x5f0\n netif_set_real_num_tx_queues+0x303/0x840\n virtnet_set_channels+0x1bf/0x260 [virtio_net]\n ethnl_set_channels+0x684/0xae0\n ethnl_default_set_doit+0x31a/0x890\n ...\n\nSerialize qdisc_reset_all_tx_gt() against the lockless dequeue path by\ntaking qdisc->seqlock for TCQ_F_NOLOCK qdiscs, matching the\nserialization model already used by dev_reset_queue().\n\nAdditionally clear QDISC_STATE_NON_EMPTY after reset so the qdisc state\nreflects an empty queue, avoiding needless re-scheduling." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - Triggered via ethtool netlink (ETHTOOL_MSG_CHANNELS_SET) which requires local access through a netlink socket. Not reachable from the network.\nAC:L - The attacker controls both sides of the race — sending traffic and changing channel count simultaneously. The commit message confirms this is \"easily reproduced\" with concurrent iperf and ethtool.\nPR:L - ETHTOOL_MSG_CHANNELS_SET uses GENL_UNS_ADMIN_PERM, which checks CAP_NET_ADMIN in the user namespace via netlink_ns_capable(). Veth devices support set_channels and can be created in user namespaces, so an unprivileged user can trigger this via unshare -Urn.\nUI:N - No user interaction is required. The attacker can independently trigger both the traffic and channel reconfiguration.\nS:U - Standard kernel use-after-free within the same security authority (kernel). No cross-boundary impact like VM escape.\nC:H - This is a use-after-free on sk_buff objects. The freed skb memory can be reallocated with attacker-controlled content, enabling reading of arbitrary kernel memory through the dangling pointer.\nI:H - UAF on sk_buff objects allows heap spraying — the freed skb slab can be reclaimed with attacker-controlled data, enabling arbitrary write primitives and potential code execution.\nA:H - The KASAN report confirms a slab-use-after-free crash in __qdisc_run. This causes a kernel oops/panic, and is easily and repeatedly triggerable." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/sch_generic.h" ], "versions": [ { "version": "6b3ba9146fe64b9bebb6346c9dcfe3b4851de2d7", "lessThan": "5bb27ad54d12de67e457d7d251198e361bef835e", "status": "affected", "versionType": "git" }, { "version": "6b3ba9146fe64b9bebb6346c9dcfe3b4851de2d7", "lessThan": "7594467c49bfc2f4644dee0415ac2290db11fa0d", "status": "affected", "versionType": "git" }, { "version": "6b3ba9146fe64b9bebb6346c9dcfe3b4851de2d7", "lessThan": "dbd58b0730aa06ab6ad26079cf9a5b6b58e7e750", "status": "affected", "versionType": "git" }, { "version": "6b3ba9146fe64b9bebb6346c9dcfe3b4851de2d7", "lessThan": "5bc4e69306ed7ae02232eb4c0b23ed621a26d504", "status": "affected", "versionType": "git" }, { "version": "6b3ba9146fe64b9bebb6346c9dcfe3b4851de2d7", "lessThan": "8314944cc3bdeaa5a73e6f8a8cf0d94822e625cb", "status": "affected", "versionType": "git" }, { "version": "6b3ba9146fe64b9bebb6346c9dcfe3b4851de2d7", "lessThan": "c69df4e0524f8de8e176ba389acd83e85f5f49d0", "status": "affected", "versionType": "git" }, { "version": "6b3ba9146fe64b9bebb6346c9dcfe3b4851de2d7", "lessThan": "7f083faf59d14c04e01ec05a7507f036c965acf8", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/sch_generic.h" ], "versions": [ { "version": "4.16", "status": "affected" }, { "version": "0", "lessThan": "4.16", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.203", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.167", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.130", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.77", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.17", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.7", "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": "4.16", "versionEndExcluding": "5.15.203" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.1.167" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.6.130" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.12.77" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.18.17" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.19.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/5bb27ad54d12de67e457d7d251198e361bef835e" }, { "url": "https://git.kernel.org/stable/c/7594467c49bfc2f4644dee0415ac2290db11fa0d" }, { "url": "https://git.kernel.org/stable/c/dbd58b0730aa06ab6ad26079cf9a5b6b58e7e750" }, { "url": "https://git.kernel.org/stable/c/5bc4e69306ed7ae02232eb4c0b23ed621a26d504" }, { "url": "https://git.kernel.org/stable/c/8314944cc3bdeaa5a73e6f8a8cf0d94822e625cb" }, { "url": "https://git.kernel.org/stable/c/c69df4e0524f8de8e176ba389acd83e85f5f49d0" }, { "url": "https://git.kernel.org/stable/c/7f083faf59d14c04e01ec05a7507f036c965acf8" } ], "title": "net: sched: avoid qdisc_reset_all_tx_gt() vs dequeue race for lockless qdiscs", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-07-14T12:46:37.600Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": 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