Linux: Use After Free
CVE-2026-64423 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 412ba7def06ffe974ba9a1d862b022362c54ffa5, c6cb5f8ebe1c1a78710c19f102db9fe48b9e6ba9, 5f42729d74bd6c61306d864423290d92962de4e1 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.13% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 412ba7def06ffe974ba9a1d862b022362c54ffa5 or c6cb5f8ebe1c1a78710c19f102db9fe48b9e6ba9 or 5f42729d74bd6c61306d864423290d92962de4e1 or 76d030ac95e17f91d69a595f17ebc5979700cf9a, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.261 or 5.15.212 or 6.1.178 or 6.6.145, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | e9897071350bd9d94a56b5b6f79c85b1a98fc7e7 up to, but not including, 412ba7def06ffe974ba9a1d862b022362c54ffa5; e9897071350bd9d94a56b5b6f79c85b1a98fc7e7 up to, but not including, c6cb5f8ebe1c1a78710c19f102db9fe48b9e6ba9; e9897071350bd9d94a56b5b6f79c85b1a98fc7e7 up to, but not including, 5f42729d74bd6c61306d864423290d92962de4e1; e9897071350bd9d94a56b5b6f79c85b1a98fc7e7 up to, but not including, 76d030ac95e17f91d69a595f17ebc5979700cf9a; e9897071350bd9d94a56b5b6f79c85b1a98fc7e7 up to, but not including, 8820b530cb2388503d7418228d03ba074bf7a03e; e9897071350bd9d94a56b5b6f79c85b1a98fc7e7 up to, but not including, 2ca18df1c2611f70eb3eb487e02ae85eb703b284; e9897071350bd9d94a56b5b6f79c85b1a98fc7e7 up to, but not including, f91883031e5a62877a29ce139442973cbea769f1; e9897071350bd9d94a56b5b6f79c85b1a98fc7e7 up to, but not including, 7993211bde166471dffac074dc965489f86531f8; and 1 more ranges | 412ba7def06ffe974ba9a1d862b022362c54ffa5, c6cb5f8ebe1c1a78710c19f102db9fe48b9e6ba9, 5f42729d74bd6c61306d864423290d92962de4e1, 76d030ac95e17f91d69a595f17ebc5979700cf9a, 8820b530cb2388503d7418228d03ba074bf7a03e, 2ca18df1c2611f70eb3eb487e02ae85eb703b284 |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Linux | Linux Kernel | 3.11 up to, but not including, 5.10.261; 5.11 up to, but not including, 5.15.212; 5.16 up to, but not including, 6.1.178; 6.2 up to, but not including, 6.6.145; 6.7 up to, but not including, 6.12.96; 6.13 up to, but not including, 6.18.39; 6.19 up to, but not including, 7.1.4; 7.2 | 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.39 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.
Official 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
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/2ca18df1c2611f70eb3eb487e02ae85eb703b284
- git.kernel.org/stable/c/412ba7def06ffe974ba9a1d862b022362c54ffa5
- git.kernel.org/stable/c/5f42729d74bd6c61306d864423290d92962de4e1
- git.kernel.org/stable/c/76d030ac95e17f91d69a595f17ebc5979700cf9a
- git.kernel.org/stable/c/7993211bde166471dffac074dc965489f86531f8
- git.kernel.org/stable/c/8820b530cb2388503d7418228d03ba074bf7a03e
- git.kernel.org/stable/c/c6cb5f8ebe1c1a78710c19f102db9fe48b9e6ba9
- git.kernel.org/stable/c/f91883031e5a62877a29ce139442973cbea769f1
Other references
Recent Use After Free vulnerabilities
- 9.8 Critical severity
- 7.8 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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