Linux: Use After Free
CVE-2026-72080 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 7b7bb07efe41bb646a93c4624aa2bb35df190342, 7d330a1d663381579b9d5dafa642b1b3158a0ce2, 52fce648607e0d6a76eeb443d78708c49df1c554 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 0.17% 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 7b7bb07efe41bb646a93c4624aa2bb35df190342 or 7d330a1d663381579b9d5dafa642b1b3158a0ce2 or 52fce648607e0d6a76eeb443d78708c49df1c554, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 2a65660385444e9d9deffe995c71ee20443ef76e up to, but not including, 7b7bb07efe41bb646a93c4624aa2bb35df190342; 2a65660385444e9d9deffe995c71ee20443ef76e up to, but not including, 7d330a1d663381579b9d5dafa642b1b3158a0ce2; 2a65660385444e9d9deffe995c71ee20443ef76e up to, but not including, 52fce648607e0d6a76eeb443d78708c49df1c554; 6.16 | 7b7bb07efe41bb646a93c4624aa2bb35df190342, 7d330a1d663381579b9d5dafa642b1b3158a0ce2, 52fce648607e0d6a76eeb443d78708c49df1c554 |
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: fs/resctrl: Fix use-after-free during unmount During unmount or failure teardown all mon_data structures that contain monitoring event file private data are freed after which kernfs nodes are removed. However, the RDT_DELETED flag is never set for the statically allocated default resource group. A concurrent reader of an event file associated with the default resource group may, after dropping kernfs active protection, block on rdtgroup_mutex while unmount proceeds to free the file private data and destroy the kernfs node without waiting for the reader. When the mutex is released, the reader wakes up, observes that RDT_DELETED is not set for the default group, and dereferences the already-freed file private data. The scenario can be depicted as follows: CPU0 CPU1 /* * Default resource group's * monitoring data accessible via * kernfs file with kernfs_node::priv * pointing to a struct mon_data. * User opens the file for reading. */ rdtgroup_mondata_show() /* arch encounters fatal error */ rdtgroup_kn_lock_live() resctrl_exit() atomic_inc(&rdtgroup_default.waitcount) cpus_read_lock() kernfs_break_active_protection(kn) mutex_lock(&rdtgroup_mutex) cpus_read_lock() resctrl_fs_teardown() mutex_lock(&rdtgroup_mutex) rmdir_all_sub() mon_put_kn_priv() /* Delete all mon_data structures */ rdtgroup_destroy_root() kernfs_destroy_root() rdtgroup_default.kn = NULL mutex_unlock(&rdtgroup_mutex) /* * rdtgroup_default.flags is empty so * rdtgroup_kn_lock_live() returns * &rdtgroup_default */ md = of->kn->priv; /* md points to freed mon_data */ Set RDT_DELETED for the default group unconditionally since the flag does not lead to the freeing of this statically allocated group. Do not allow a new resctrl mount if there are any waiters on default group of previous mount. A new mount will re-initialize the default group that would appear to waiters from previous mount as though the default group is accessible causing them to access the mon_data structures from the previous mount that have been removed.
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
Other references
Recent Use After Free vulnerabilities
- 9.3 Critical severity
- 9.8 Critical severity
- 7.8 High severity
- 9.8 Critical severity
- 8.8 High severity
- 7.8 High severity
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