Linux: Use After Free
CVE-2026-64123 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 0ea70fb46940620848c08d9d399455c9e82fecdb, 8be6685cdd1255bcc85f9b59e4bfc313aefc5c1b, c5580114e0492bcd2e0a37613ed4c311e3fa3d4d 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 0ea70fb46940620848c08d9d399455c9e82fecdb or 8be6685cdd1255bcc85f9b59e4bfc313aefc5c1b or c5580114e0492bcd2e0a37613ed4c311e3fa3d4d or 7713f4aafb577ff49fa67f0488d9c7dddc64d6ce, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.259 or 5.15.210 or 6.1.176 or 6.6.143, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | b9a1e627405d68d475a3c1f35e685ccfb5bbe668 up to, but not including, 0ea70fb46940620848c08d9d399455c9e82fecdb; b9a1e627405d68d475a3c1f35e685ccfb5bbe668 up to, but not including, 8be6685cdd1255bcc85f9b59e4bfc313aefc5c1b; b9a1e627405d68d475a3c1f35e685ccfb5bbe668 up to, but not including, c5580114e0492bcd2e0a37613ed4c311e3fa3d4d; b9a1e627405d68d475a3c1f35e685ccfb5bbe668 up to, but not including, 7713f4aafb577ff49fa67f0488d9c7dddc64d6ce; b9a1e627405d68d475a3c1f35e685ccfb5bbe668 up to, but not including, 6324423a8e6591f41a16c09a8f9a84e554ac147c; b9a1e627405d68d475a3c1f35e685ccfb5bbe668 up to, but not including, 48d09dea506de667eb55f939bf98eec721effbdb; b9a1e627405d68d475a3c1f35e685ccfb5bbe668 up to, but not including, 8c3af18bb0d7c921a5219194037509463eb2ffde; b9a1e627405d68d475a3c1f35e685ccfb5bbe668 up to, but not including, aaec7096f9961eb223b5b149abe9495525c205d9; and 3 more ranges | 0ea70fb46940620848c08d9d399455c9e82fecdb, 8be6685cdd1255bcc85f9b59e4bfc313aefc5c1b, c5580114e0492bcd2e0a37613ed4c311e3fa3d4d, 7713f4aafb577ff49fa67f0488d9c7dddc64d6ce, 6324423a8e6591f41a16c09a8f9a84e554ac147c, 48d09dea506de667eb55f939bf98eec721effbdb |
| Linux | Linux Kernel | 5.2.12 up to, but not including, 5.10.259; 5.11 up to, but not including, 5.15.210; 5.16 up to, but not including, 6.1.176; 6.2 up to, but not including, 6.6.143; 6.7 up to, but not including, 6.12.93; 6.13 up to, but not including, 7.0.11; 7.1 | 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, 7.0.11 |
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: 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().
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/0ea70fb46940620848c08d9d399455c9e82fecdb
- git.kernel.org/stable/c/6324423a8e6591f41a16c09a8f9a84e554ac147c
- git.kernel.org/stable/c/7713f4aafb577ff49fa67f0488d9c7dddc64d6ce
- git.kernel.org/stable/c/8be6685cdd1255bcc85f9b59e4bfc313aefc5c1b
- git.kernel.org/stable/c/8c3af18bb0d7c921a5219194037509463eb2ffde
- git.kernel.org/stable/c/aaec7096f9961eb223b5b149abe9495525c205d9
- git.kernel.org/stable/c/c5580114e0492bcd2e0a37613ed4c311e3fa3d4d
Other references
Recent Use After Free vulnerabilities
- 8.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
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