CVE-2026-23004 - Vulnerability Details

Vendors	Products
Linux	Linux Kernel

Link	Providers
https://git.kernel.org/stable/c/722de945216144af7cd4d39bdeb936108d2595a7
https://git.kernel.org/stable/c/9a6f0c4d5796ab89b5a28a890ce542344d58bd69

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: dst: fix races in rt6_uncached_list_del() and rt_del_uncached_list() syzbot was able to crash the kernel in rt6_uncached_list_flush_dev() in an interesting way [1] Crash happens in list_del_init()/INIT_LIST_HEAD() while writing list->prev, while the prior write on list->next went well. static inline void INIT_LIST_HEAD(struct list_head *list) { WRITE_ONCE(list->next, list); // This went well WRITE_ONCE(list->prev, list); // Crash, @list has been freed. } Issue here is that rt6_uncached_list_del() did not attempt to lock ul->lock, as list_empty(&rt->dst.rt_uncached) returned true because the WRITE_ONCE(list->next, list) happened on the other CPU. We might use list_del_init_careful() and list_empty_careful(), or make sure rt6_uncached_list_del() always grabs the spinlock whenever rt->dst.rt_uncached_list has been set. A similar fix is neeed for IPv4. [1] BUG: KASAN: slab-use-after-free in INIT_LIST_HEAD include/linux/list.h:46 [inline] BUG: KASAN: slab-use-after-free in list_del_init include/linux/list.h:296 [inline] BUG: KASAN: slab-use-after-free in rt6_uncached_list_flush_dev net/ipv6/route.c:191 [inline] BUG: KASAN: slab-use-after-free in rt6_disable_ip+0x633/0x730 net/ipv6/route.c:5020 Write of size 8 at addr ffff8880294cfa78 by task kworker/u8:14/3450 CPU: 0 UID: 0 PID: 3450 Comm: kworker/u8:14 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: netns cleanup_net Call Trace: <TASK> dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xca/0x240 mm/kasan/report.c:482 kasan_report+0x118/0x150 mm/kasan/report.c:595 INIT_LIST_HEAD include/linux/list.h:46 [inline] list_del_init include/linux/list.h:296 [inline] rt6_uncached_list_flush_dev net/ipv6/route.c:191 [inline] rt6_disable_ip+0x633/0x730 net/ipv6/route.c:5020 addrconf_ifdown+0x143/0x18a0 net/ipv6/addrconf.c:3853 addrconf_notify+0x1bc/0x1050 net/ipv6/addrconf.c:-1 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline] call_netdevice_notifiers net/core/dev.c:2282 [inline] netif_close_many+0x29c/0x410 net/core/dev.c:1785 unregister_netdevice_many_notify+0xb50/0x2330 net/core/dev.c:12353 ops_exit_rtnl_list net/core/net_namespace.c:187 [inline] ops_undo_list+0x3dc/0x990 net/core/net_namespace.c:248 cleanup_net+0x4de/0x7b0 net/core/net_namespace.c:696 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 </TASK> Allocated by task 803: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4953 [inline] slab_alloc_node mm/slub.c:5263 [inline] kmem_cache_alloc_noprof+0x18d/0x6c0 mm/slub.c:5270 dst_alloc+0x105/0x170 net/core/dst.c:89 ip6_dst_alloc net/ipv6/route.c:342 [inline] icmp6_dst_alloc+0x75/0x460 net/ipv6/route.c:3333 mld_sendpack+0x683/0xe60 net/ipv6/mcast.c:1844 mld_send_cr net/ipv6/mcast.c:2154 [inline] mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entr ---truncated---
Title		dst: fix races in rt6_uncached_list_del() and rt_del_uncached_list()
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/722de945216144af7cd4d39bdeb936108d2595a7 https://git.kernel.org/stable/c/9a6f0c4d5796ab89b5a28a890ce542344d58bd69

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-23004", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-01-13T15:37:45.939Z", "datePublished": "2026-01-25T14:36:18.233Z", "dateUpdated": "2026-01-25T14:36:18.233Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-01-25T14:36:18.233Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndst: fix races in rt6_uncached_list_del() and rt_del_uncached_list()\n\nsyzbot was able to crash the kernel in rt6_uncached_list_flush_dev()\nin an interesting way [1]\n\nCrash happens in list_del_init()/INIT_LIST_HEAD() while writing\nlist->prev, while the prior write on list->next went well.\n\nstatic inline void INIT_LIST_HEAD(struct list_head *list)\n{\n\tWRITE_ONCE(list->next, list); // This went well\n\tWRITE_ONCE(list->prev, list); // Crash, @list has been freed.\n}\n\nIssue here is that rt6_uncached_list_del() did not attempt to lock\nul->lock, as list_empty(&rt->dst.rt_uncached) returned\ntrue because the WRITE_ONCE(list->next, list) happened on the other CPU.\n\nWe might use list_del_init_careful() and list_empty_careful(),\nor make sure rt6_uncached_list_del() always grabs the spinlock\nwhenever rt->dst.rt_uncached_list has been set.\n\nA similar fix is neeed for IPv4.\n\n[1]\n\n BUG: KASAN: slab-use-after-free in INIT_LIST_HEAD include/linux/list.h:46 [inline]\n BUG: KASAN: slab-use-after-free in list_del_init include/linux/list.h:296 [inline]\n BUG: KASAN: slab-use-after-free in rt6_uncached_list_flush_dev net/ipv6/route.c:191 [inline]\n BUG: KASAN: slab-use-after-free in rt6_disable_ip+0x633/0x730 net/ipv6/route.c:5020\nWrite of size 8 at addr ffff8880294cfa78 by task kworker/u8:14/3450\n\nCPU: 0 UID: 0 PID: 3450 Comm: kworker/u8:14 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}\nTainted: [L]=SOFTLOCKUP\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025\nWorkqueue: netns cleanup_net\nCall Trace:\n <TASK>\n dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120\n print_address_description mm/kasan/report.c:378 [inline]\n print_report+0xca/0x240 mm/kasan/report.c:482\n kasan_report+0x118/0x150 mm/kasan/report.c:595\n INIT_LIST_HEAD include/linux/list.h:46 [inline]\n list_del_init include/linux/list.h:296 [inline]\n rt6_uncached_list_flush_dev net/ipv6/route.c:191 [inline]\n rt6_disable_ip+0x633/0x730 net/ipv6/route.c:5020\n addrconf_ifdown+0x143/0x18a0 net/ipv6/addrconf.c:3853\n addrconf_notify+0x1bc/0x1050 net/ipv6/addrconf.c:-1\n notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85\n call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]\n call_netdevice_notifiers net/core/dev.c:2282 [inline]\n netif_close_many+0x29c/0x410 net/core/dev.c:1785\n unregister_netdevice_many_notify+0xb50/0x2330 net/core/dev.c:12353\n ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]\n ops_undo_list+0x3dc/0x990 net/core/net_namespace.c:248\n cleanup_net+0x4de/0x7b0 net/core/net_namespace.c:696\n process_one_work kernel/workqueue.c:3257 [inline]\n process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340\n worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421\n kthread+0x711/0x8a0 kernel/kthread.c:463\n ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246\n </TASK>\n\nAllocated by task 803:\n kasan_save_stack mm/kasan/common.c:57 [inline]\n kasan_save_track+0x3e/0x80 mm/kasan/common.c:78\n unpoison_slab_object mm/kasan/common.c:340 [inline]\n __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366\n kasan_slab_alloc include/linux/kasan.h:253 [inline]\n slab_post_alloc_hook mm/slub.c:4953 [inline]\n slab_alloc_node mm/slub.c:5263 [inline]\n kmem_cache_alloc_noprof+0x18d/0x6c0 mm/slub.c:5270\n dst_alloc+0x105/0x170 net/core/dst.c:89\n ip6_dst_alloc net/ipv6/route.c:342 [inline]\n icmp6_dst_alloc+0x75/0x460 net/ipv6/route.c:3333\n mld_sendpack+0x683/0xe60 net/ipv6/mcast.c:1844\n mld_send_cr net/ipv6/mcast.c:2154 [inline]\n mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693\n process_one_work kernel/workqueue.c:3257 [inline]\n process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340\n worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421\n kthread+0x711/0x8a0 kernel/kthread.c:463\n ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entr\n---truncated---"}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/core/dst.c", "net/ipv4/route.c", "net/ipv6/route.c"], "versions": [{"version": "78df76a065ae3b5dbcb9a29912adc02f697de498", "lessThan": "722de945216144af7cd4d39bdeb936108d2595a7", "status": "affected", "versionType": "git"}, {"version": "78df76a065ae3b5dbcb9a29912adc02f697de498", "lessThan": "9a6f0c4d5796ab89b5a28a890ce542344d58bd69", "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/dst.c", "net/ipv4/route.c", "net/ipv6/route.c"], "versions": [{"version": "3.6", "status": "affected"}, {"version": "0", "lessThan": "3.6", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.7", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.19-rc6", "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": "3.6", "versionEndExcluding": "6.18.7"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.6", "versionEndExcluding": "6.19-rc6"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/722de945216144af7cd4d39bdeb936108d2595a7"}, {"url": "https://git.kernel.org/stable/c/9a6f0c4d5796ab89b5a28a890ce542344d58bd69"}], "title": "dst: fix races in rt6_uncached_list_del() and rt_del_uncached_list()", "x_generator": {"engine": "bippy-1.2.0"}}}}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndst: fix races in rt6_uncached_list_del() and rt_del_uncached_list()\n\nsyzbot was able to crash the kernel in rt6_uncached_list_flush_dev()\nin an interesting way [1]\n\nCrash happens in list_del_init()/INIT_LIST_HEAD() while writing\nlist->prev, while the prior write on list->next went well.\n\nstatic inline void INIT_LIST_HEAD(struct list_head *list)\n{\n\tWRITE_ONCE(list->next, list); // This went well\n\tWRITE_ONCE(list->prev, list); // Crash, @list has been freed.\n}\n\nIssue here is that rt6_uncached_list_del() did not attempt to lock\nul->lock, as list_empty(&rt->dst.rt_uncached) returned\ntrue because the WRITE_ONCE(list->next, list) happened on the other CPU.\n\nWe might use list_del_init_careful() and list_empty_careful(),\nor make sure rt6_uncached_list_del() always grabs the spinlock\nwhenever rt->dst.rt_uncached_list has been set.\n\nA similar fix is neeed for IPv4.\n\n[1]\n\n BUG: KASAN: slab-use-after-free in INIT_LIST_HEAD include/linux/list.h:46 [inline]\n BUG: KASAN: slab-use-after-free in list_del_init include/linux/list.h:296 [inline]\n BUG: KASAN: slab-use-after-free in rt6_uncached_list_flush_dev net/ipv6/route.c:191 [inline]\n BUG: KASAN: slab-use-after-free in rt6_disable_ip+0x633/0x730 net/ipv6/route.c:5020\nWrite of size 8 at addr ffff8880294cfa78 by task kworker/u8:14/3450\n\nCPU: 0 UID: 0 PID: 3450 Comm: kworker/u8:14 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}\nTainted: [L]=SOFTLOCKUP\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025\nWorkqueue: netns cleanup_net\nCall Trace:\n <TASK>\n dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120\n print_address_description mm/kasan/report.c:378 [inline]\n print_report+0xca/0x240 mm/kasan/report.c:482\n kasan_report+0x118/0x150 mm/kasan/report.c:595\n INIT_LIST_HEAD include/linux/list.h:46 [inline]\n list_del_init include/linux/list.h:296 [inline]\n rt6_uncached_list_flush_dev net/ipv6/route.c:191 [inline]\n rt6_disable_ip+0x633/0x730 net/ipv6/route.c:5020\n addrconf_ifdown+0x143/0x18a0 net/ipv6/addrconf.c:3853\n addrconf_notify+0x1bc/0x1050 net/ipv6/addrconf.c:-1\n notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85\n call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]\n call_netdevice_notifiers net/core/dev.c:2282 [inline]\n netif_close_many+0x29c/0x410 net/core/dev.c:1785\n unregister_netdevice_many_notify+0xb50/0x2330 net/core/dev.c:12353\n ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]\n ops_undo_list+0x3dc/0x990 net/core/net_namespace.c:248\n cleanup_net+0x4de/0x7b0 net/core/net_namespace.c:696\n process_one_work kernel/workqueue.c:3257 [inline]\n process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340\n worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421\n kthread+0x711/0x8a0 kernel/kthread.c:463\n ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246\n </TASK>\n\nAllocated by task 803:\n kasan_save_stack mm/kasan/common.c:57 [inline]\n kasan_save_track+0x3e/0x80 mm/kasan/common.c:78\n unpoison_slab_object mm/kasan/common.c:340 [inline]\n __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366\n kasan_slab_alloc include/linux/kasan.h:253 [inline]\n slab_post_alloc_hook mm/slub.c:4953 [inline]\n slab_alloc_node mm/slub.c:5263 [inline]\n kmem_cache_alloc_noprof+0x18d/0x6c0 mm/slub.c:5270\n dst_alloc+0x105/0x170 net/core/dst.c:89\n ip6_dst_alloc net/ipv6/route.c:342 [inline]\n icmp6_dst_alloc+0x75/0x460 net/ipv6/route.c:3333\n mld_sendpack+0x683/0xe60 net/ipv6/mcast.c:1844\n mld_send_cr net/ipv6/mcast.c:2154 [inline]\n mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693\n process_one_work kernel/workqueue.c:3257 [inline]\n process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340\n worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421\n kthread+0x711/0x8a0 kernel/kthread.c:463\n ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entr\n---truncated---"}], "id": "CVE-2026-23004", "lastModified": "2026-01-25T15:15:55.273", "metrics": {}, "published": "2026-01-25T15:15:55.273", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/722de945216144af7cd4d39bdeb936108d2595a7"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/9a6f0c4d5796ab89b5a28a890ce542344d58bd69"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

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