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Vulnerability record · CVE-2026-64123 · published 19 July 2026

CVE-2026-64123: Linux kernel use after free vulnerability

Linux · Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: net: hsr: defer node table free until after RCU readers HSR node-list and node-status generic-netlink operations run under rcu_read_lock(). They walk hsr->node_db through hsr_get_next_node() and hsr_get_node_data(), but RTM_DELLINK teardown removes the same node table with plain list_del() and frees each node immediately. That lets a generic-netlink reader hold a struct hsr_node pointer across hsr_dellink(). In a KASAN build, widening the reader window after hsr_get_next_node() obtains the node reproduces a slab-use-after-free when the reader copies node->macaddress_A; the freeing stack is hsr_del_nodes() from hsr_dellink(). Use list_del_rcu() and defer the free through the existing hsr_free_node_rcu() callback. This matches the lifetime rule used by the HSR prune paths, which already delete nodes with list_del_rcu() and call_rcu().

7.8 CVSS 3.1 High EPSS 0.17% · top 94.2% CWE-416 · Use after free
7.8CVSS 3.1 base score
0.17%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
7References
13 Aug 2026Last modified by NVD

Description

In the Linux kernel, the following vulnerability has been resolved: net: hsr: defer node table free until after RCU readers HSR node-list and node-status generic-netlink operations run under rcu_read_lock(). They walk hsr->node_db through hsr_get_next_node() and hsr_get_node_data(), but RTM_DELLINK teardown removes the same node table with plain list_del() and frees each node immediately. That lets a generic-netlink reader hold a struct hsr_node pointer across hsr_dellink(). In a KASAN build, widening the reader window after hsr_get_next_node() obtains the node reproduces a slab-use-after-free when the reader copies node->macaddress_A; the freeing stack is hsr_del_nodes() from hsr_dellink(). Use list_del_rcu() and defer the free through the existing hsr_free_node_rcu() callback. This matches the lifetime rule used by the HSR prune paths, which already delete nodes with list_del_rcu() and call_rcu().

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://git.kernel.org/stable/c/0ea70fb46940620848c08d9d399455c9e82fecdb Patch
https://git.kernel.org/stable/c/6324423a8e6591f41a16c09a8f9a84e554ac147c Patch
https://git.kernel.org/stable/c/7713f4aafb577ff49fa67f0488d9c7dddc64d6ce Patch
https://git.kernel.org/stable/c/8be6685cdd1255bcc85f9b59e4bfc313aefc5c1b Patch
https://git.kernel.org/stable/c/8c3af18bb0d7c921a5219194037509463eb2ffde Patch
https://git.kernel.org/stable/c/aaec7096f9961eb223b5b149abe9495525c205d9 Patch
https://git.kernel.org/stable/c/c5580114e0492bcd2e0a37613ed4c311e3fa3d4d Patch

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Source: NIST National Vulnerability Database (record CVE-2026-64123), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.