# CVE-2026-64423: ipv4: igmp: remove multicast group from hash table on device destruction

Status: published. Published: 2026-07-25. Updated: 2026-11-10.

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

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ e9897071350bd9d94a56b5b6f79c85b1a98fc7e7; < 412ba7def06ffe974ba9a1d862b022362c54ffa5 (affected, git); ≥ e9897071350bd9d94a56b5b6f79c85b1a98fc7e7; < c6cb5f8ebe1c1a78710c19f102db9fe48b9e6ba9 (affected, git); ≥ e9897071350bd9d94a56b5b6f79c85b1a98fc7e7; < 5f42729d74bd6c61306d864423290d92962de4e1 (affected, git); ≥ e9897071350bd9d94a56b5b6f79c85b1a98fc7e7; < 76d030ac95e17f91d69a595f17ebc5979700cf9a (affected, git); ≥ e9897071350bd9d94a56b5b6f79c85b1a98fc7e7; < 8820b530cb2388503d7418228d03ba074bf7a03e (affected, git); ≥ e9897071350bd9d94a56b5b6f79c85b1a98fc7e7; < 2ca18df1c2611f70eb3eb487e02ae85eb703b284 (affected, git); ≥ e9897071350bd9d94a56b5b6f79c85b1a98fc7e7; < f91883031e5a62877a29ce139442973cbea769f1 (affected, git); ≥ e9897071350bd9d94a56b5b6f79c85b1a98fc7e7; < 7993211bde166471dffac074dc965489f86531f8 (affected, git). Source: CNA: Linux
- Linux / Linux: 3.11 (affected); ≥ 0; < 3.11 (unaffected, semver); ≥ 5.10.261; ≤ 5.10.* (unaffected, semver); ≥ 5.15.212; ≤ 5.15.* (unaffected, semver); ≥ 6.1.178; ≤ 6.1.* (unaffected, semver); ≥ 6.6.145; ≤ 6.6.* (unaffected, semver); ≥ 6.12.96; ≤ 6.12.* (unaffected, semver); ≥ 6.18.39; ≤ 6.18.* (unaffected, semver); ≥ 7.1.4; ≤ 7.1.* (unaffected, semver); ≥ 7.2; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0): ≥ V3.1.6; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP

## Severity and prioritization

- CVSS 3.1: 7.8 (high); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H; source: CNA: Linux

- CISA KEV: No listing in collected sources

- EPSS: 0.13% as of 2026-11-09; percentile 2.77%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-416

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/412ba7def06ffe974ba9a1d862b022362c54ffa5 (CNA: Linux)

- https://git.kernel.org/stable/c/c6cb5f8ebe1c1a78710c19f102db9fe48b9e6ba9 (CNA: Linux)

- https://git.kernel.org/stable/c/5f42729d74bd6c61306d864423290d92962de4e1 (CNA: Linux)

- https://git.kernel.org/stable/c/76d030ac95e17f91d69a595f17ebc5979700cf9a (CNA: Linux)

- https://git.kernel.org/stable/c/8820b530cb2388503d7418228d03ba074bf7a03e (CNA: Linux)

- https://git.kernel.org/stable/c/2ca18df1c2611f70eb3eb487e02ae85eb703b284 (CNA: Linux)

- https://git.kernel.org/stable/c/f91883031e5a62877a29ce139442973cbea769f1 (CNA: Linux)

- https://git.kernel.org/stable/c/7993211bde166471dffac074dc965489f86531f8 (CNA: Linux)

- https://cert-portal.siemens.com/productcert/html/ssa-019113.html (ADP: siemens-SADP)

- https://cert-portal.siemens.com/productcert/html/ssa-457936.html (ADP: siemens-SADP)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-64423; retrieved 2026-11-10; source updated 2026-11-10

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-64423; retrieved 2026-11-10; source updated Not reported

Revision: 85506617f09f5d7eaa56a072a61bd9ca493c74f4b8cd4816763bc98564eb7f9c

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