Linux: Use After Free
CVE-2026-46259 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 fefa0fcd78be465b7ad4c497fa6ec90d64194c04, c93a33f28f915d446eea6fb3f0e1def0b3af1982, 1c8dc5b5517546c68ffae40b948336122bb61306 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 0.12% 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 fefa0fcd78be465b7ad4c497fa6ec90d64194c04 or c93a33f28f915d446eea6fb3f0e1def0b3af1982 or 1c8dc5b5517546c68ffae40b948336122bb61306 or 0e64bd46a04a4fd61279aca9f53a664e9e5f7e7e, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.252 or 5.15.202 or 6.1.165 or 6.6.128, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 06fffb1267c9d986687b69d74a46ee332a50575e up to, but not including, fefa0fcd78be465b7ad4c497fa6ec90d64194c04; 06fffb1267c9d986687b69d74a46ee332a50575e up to, but not including, c93a33f28f915d446eea6fb3f0e1def0b3af1982; 06fffb1267c9d986687b69d74a46ee332a50575e up to, but not including, 1c8dc5b5517546c68ffae40b948336122bb61306; 06fffb1267c9d986687b69d74a46ee332a50575e up to, but not including, 0e64bd46a04a4fd61279aca9f53a664e9e5f7e7e; 06fffb1267c9d986687b69d74a46ee332a50575e up to, but not including, 73ec7c96601d61d52310c659145bb06d933a0fa6; 06fffb1267c9d986687b69d74a46ee332a50575e up to, but not including, 4f9ae386861e280b7631ca252f798d25575627ee; 06fffb1267c9d986687b69d74a46ee332a50575e up to, but not including, dd8b13cb4ff1a4545a214ed897fdf2bc341155b6; 06fffb1267c9d986687b69d74a46ee332a50575e up to, but not including, 76149d53502cf17ef3ae454ff384551236fba867; and 1 more ranges | fefa0fcd78be465b7ad4c497fa6ec90d64194c04, c93a33f28f915d446eea6fb3f0e1def0b3af1982, 1c8dc5b5517546c68ffae40b948336122bb61306, 0e64bd46a04a4fd61279aca9f53a664e9e5f7e7e, 73ec7c96601d61d52310c659145bb06d933a0fa6, 4f9ae386861e280b7631ca252f798d25575627ee |
| Linux | Linux Kernel | 2.6.26 up to, but not including, 5.10.252; 5.11 up to, but not including, 5.15.202; 5.16 up to, but not including, 6.1.165; 6.2 up to, but not including, 6.6.128; 6.7 up to, but not including, 6.12.75; 6.13 up to, but not including, 6.18.14; 6.19 up to, but not including, 6.19.4 | 5.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.14 |
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: procfs: fix missing RCU protection when reading real_parent in do_task_stat() When reading /proc/[pid]/stat, do_task_stat() accesses task->real_parent without proper RCU protection, which leads to: cpu 0 cpu 1 ----- ----- do_task_stat var = task->real_parent release_task call_rcu(delayed_put_task_struct) task_tgid_nr_ns(var) rcu_read_lock <--- Too late to protect task->real_parent! task_pid_ptr <--- UAF! rcu_read_unlock This patch uses task_ppid_nr_ns() instead of task_tgid_nr_ns() to add proper RCU protection for accessing task->real_parent.
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/0e64bd46a04a4fd61279aca9f53a664e9e5f7e7e
- git.kernel.org/stable/c/1c8dc5b5517546c68ffae40b948336122bb61306
- git.kernel.org/stable/c/4f9ae386861e280b7631ca252f798d25575627ee
- git.kernel.org/stable/c/73ec7c96601d61d52310c659145bb06d933a0fa6
- git.kernel.org/stable/c/76149d53502cf17ef3ae454ff384551236fba867
- git.kernel.org/stable/c/c93a33f28f915d446eea6fb3f0e1def0b3af1982
- git.kernel.org/stable/c/dd8b13cb4ff1a4545a214ed897fdf2bc341155b6
- git.kernel.org/stable/c/fefa0fcd78be465b7ad4c497fa6ec90d64194c04
Recent Use After Free vulnerabilities
- 8.4 High 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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