In the Linux kernel, the following vulnerability has been resolved: ipv4: igmp: remove multicast group from hash table on device destruction When a… (CVE-2026-64423)
In the Linux kernel, the following vulnerability has been resolved: ipv4: igmp: remove multicast group from hash table on device destruction When a device is destroyed under RTNL, ip_mc_destroy_dev() iterates through the multicast list and calls ip_ma_put() on each membership, scheduling them for RCU reclamation. However, they are not unlinked from the device's multicast hash table (mc_hash). Since the device remains published in dev->ip_ptr until after ip_mc_destroy_dev() completes, concurrent RCU readers traversing mc_hash can still locate and access the multicast group after its refcount is decremented. If the RCU callback runs and frees the group while a reader is accessing it, a use-after-free occurs. Fix this by unlinking the multicast group from mc_hash using ip_mc_hash_remove() before scheduling it for reclamation. BUG: KASAN: slab-use-after-free in ip_check_mc_rcu+0x149/0x3f0 Read of size 4 at addr ffff888009bf1408 by task mausezahn/2276 Call Trace: <IRQ> dump_stack_lvl+0x67/0x90 print_report+0x175/0x7c0 kasan_report+0x147/0x180 ip_check_mc_rcu+0x149/0x3f0 udp_v4_early_demux+0x36d/0x12d0 ip_rcv_finish_core+0xb8b/0x1390 ip_rcv_finish+0x54/0x120 NF_HOOK+0x213/0x2b0 __netif_receive_skb+0x126/0x340 process_backlog+0x4f2/0xf00 __napi_poll+0x92/0x2c0 net_rx_action+0x583/0xc60 handle_softirqs+0x236/0x7f0 do_softirq+0x57/0x80 </IRQ> Allocated by task 2239: kasan_save_track+0x3e/0x80 __kasan_kmalloc+0x72/0x90 ____ip_mc_inc_group+0x31a/0xa40 __ip_mc_join_group+0x334/0x3f0 do_ip_setsockopt+0x16fa/0x2010 ip_setsockopt+0x3f/0x90 do_sock_setsockopt+0x1ad/0x300 Freed by task 0: kasan_save_track+0x3e/0x80 kasan_save_free_info+0x40/0x50 __kasan_slab_free+0x3a/0x60 __rcu_free_sheaf_prepare+0xd4/0x220 rcu_free_sheaf+0x36/0x190 rcu_core+0x8d9/0x12f0 handle_softirqs+0x236/0x7f0
AI Analysis
Technical Summary
CVE-2026-64423 describes a use-after-free vulnerability in the Linux kernel's IPv4 IGMP implementation. When a network device is destroyed under RTNL, the function ip_mc_destroy_dev() iterates through multicast memberships and schedules them for RCU reclamation but fails to unlink them from the device's multicast hash table (mc_hash). Because the device remains published until after ip_mc_destroy_dev() completes, concurrent RCU readers can access multicast groups after their reference counts are decremented. If the RCU callback frees the group while a reader accesses it, a use-after-free occurs. The vulnerability is fixed by unlinking the multicast group from mc_hash using ip_mc_hash_remove() before scheduling reclamation.
Potential Impact
This vulnerability can lead to use-after-free conditions in kernel memory, which may cause kernel crashes or undefined behavior. While no specific exploit in the wild is known, such memory corruption issues can potentially be leveraged for privilege escalation or denial of service.
Mitigation Recommendations
A fix for this vulnerability has been implemented in the Linux kernel by unlinking multicast groups from the hash table before scheduling them for reclamation. Users should apply the official Linux kernel updates that include this fix. Since no patch links or vendor advisory are provided here, check the official Linux kernel repositories or vendor advisories for the relevant fixed kernel versions and update accordingly.
In the Linux kernel, the following vulnerability has been resolved: ipv4: igmp: remove multicast group from hash table on device destruction When a… (CVE-2026-64423)
Description
In the Linux kernel, the following vulnerability has been resolved: ipv4: igmp: remove multicast group from hash table on device destruction When a device is destroyed under RTNL, ip_mc_destroy_dev() iterates through the multicast list and calls ip_ma_put() on each membership, scheduling them for RCU reclamation. However, they are not unlinked from the device's multicast hash table (mc_hash). Since the device remains published in dev->ip_ptr until after ip_mc_destroy_dev() completes, concurrent RCU readers traversing mc_hash can still locate and access the multicast group after its refcount is decremented. If the RCU callback runs and frees the group while a reader is accessing it, a use-after-free occurs. Fix this by unlinking the multicast group from mc_hash using ip_mc_hash_remove() before scheduling it for reclamation. BUG: KASAN: slab-use-after-free in ip_check_mc_rcu+0x149/0x3f0 Read of size 4 at addr ffff888009bf1408 by task mausezahn/2276 Call Trace: <IRQ> dump_stack_lvl+0x67/0x90 print_report+0x175/0x7c0 kasan_report+0x147/0x180 ip_check_mc_rcu+0x149/0x3f0 udp_v4_early_demux+0x36d/0x12d0 ip_rcv_finish_core+0xb8b/0x1390 ip_rcv_finish+0x54/0x120 NF_HOOK+0x213/0x2b0 __netif_receive_skb+0x126/0x340 process_backlog+0x4f2/0xf00 __napi_poll+0x92/0x2c0 net_rx_action+0x583/0xc60 handle_softirqs+0x236/0x7f0 do_softirq+0x57/0x80 </IRQ> Allocated by task 2239: kasan_save_track+0x3e/0x80 __kasan_kmalloc+0x72/0x90 ____ip_mc_inc_group+0x31a/0xa40 __ip_mc_join_group+0x334/0x3f0 do_ip_setsockopt+0x16fa/0x2010 ip_setsockopt+0x3f/0x90 do_sock_setsockopt+0x1ad/0x300 Freed by task 0: kasan_save_track+0x3e/0x80 kasan_save_free_info+0x40/0x50 __kasan_slab_free+0x3a/0x60 __rcu_free_sheaf_prepare+0xd4/0x220 rcu_free_sheaf+0x36/0x190 rcu_core+0x8d9/0x12f0 handle_softirqs+0x236/0x7f0
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-64423 describes a use-after-free vulnerability in the Linux kernel's IPv4 IGMP implementation. When a network device is destroyed under RTNL, the function ip_mc_destroy_dev() iterates through multicast memberships and schedules them for RCU reclamation but fails to unlink them from the device's multicast hash table (mc_hash). Because the device remains published until after ip_mc_destroy_dev() completes, concurrent RCU readers can access multicast groups after their reference counts are decremented. If the RCU callback frees the group while a reader accesses it, a use-after-free occurs. The vulnerability is fixed by unlinking the multicast group from mc_hash using ip_mc_hash_remove() before scheduling reclamation.
Potential Impact
This vulnerability can lead to use-after-free conditions in kernel memory, which may cause kernel crashes or undefined behavior. While no specific exploit in the wild is known, such memory corruption issues can potentially be leveraged for privilege escalation or denial of service.
Mitigation Recommendations
A fix for this vulnerability has been implemented in the Linux kernel by unlinking multicast groups from the hash table before scheduling them for reclamation. Users should apply the official Linux kernel updates that include this fix. Since no patch links or vendor advisory are provided here, check the official Linux kernel repositories or vendor advisories for the relevant fixed kernel versions and update accordingly.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-wx6r-3m2q-4mm6
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-64423"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a6542099c2644c7f80832c6
Added to database: 07/25/2026, 23:08:57 UTC
Last enriched: 07/25/2026, 23:22:09 UTC
Last updated: 09/07/2026, 22:52:14 UTC
Views: 43
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