Linux: Use After Free
CVE-2026-43374 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 abf4feaee6405f1441929c6ebe7a250f2cd170a7, ab5ebab9664214ba41a7633cb4e72f128204f924, 9e08ad731862b22a87cc55f752e16d66cdc9e231 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 0.16% 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 abf4feaee6405f1441929c6ebe7a250f2cd170a7 or ab5ebab9664214ba41a7633cb4e72f128204f924 or 9e08ad731862b22a87cc55f752e16d66cdc9e231 or b2662e7593e94ae09b1cf7ee5f09160a3612bcb2, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.78 or 6.18.19 or 6.19.9, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | f4676ea74b8549cd88dbfe2a592ce4530039e61f up to, but not including, abf4feaee6405f1441929c6ebe7a250f2cd170a7; f4676ea74b8549cd88dbfe2a592ce4530039e61f up to, but not including, ab5ebab9664214ba41a7633cb4e72f128204f924; f4676ea74b8549cd88dbfe2a592ce4530039e61f up to, but not including, 9e08ad731862b22a87cc55f752e16d66cdc9e231; f4676ea74b8549cd88dbfe2a592ce4530039e61f up to, but not including, b2662e7593e94ae09b1cf7ee5f09160a3612bcb2; 6.9 | abf4feaee6405f1441929c6ebe7a250f2cd170a7, ab5ebab9664214ba41a7633cb4e72f128204f924, 9e08ad731862b22a87cc55f752e16d66cdc9e231, b2662e7593e94ae09b1cf7ee5f09160a3612bcb2 |
| Linux | Linux Kernel | 6.9 up to, but not including, 6.12.78; 6.13 up to, but not including, 6.18.19; 6.19 up to, but not including, 6.19.9; 6.9; 7.0 | 6.12.78, 6.18.19, 6.19.9 |
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: nexthop: fix percpu use-after-free in remove_nh_grp_entry When removing a nexthop from a group, remove_nh_grp_entry() publishes the new group via rcu_assign_pointer() then immediately frees the removed entry's percpu stats with free_percpu(). However, the synchronize_net() grace period in the caller remove_nexthop_from_groups() runs after the free. RCU readers that entered before the publish still see the old group and can dereference the freed stats via nh_grp_entry_stats_inc() -> get_cpu_ptr(nhge->stats), causing a use-after-free on percpu memory. Fix by deferring the free_percpu() until after synchronize_net() in the caller. Removed entries are chained via nh_list onto a local deferred free list. After the grace period completes and all RCU readers have finished, the percpu stats are safely freed.
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
Recent Use After Free vulnerabilities
- 7.3 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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