Linux: Use After Free
CVE-2026-68409 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists versions acd5931d5adf12f0163f83dc00320e7011f4da92, a5afc00280986063f1c355821544fabbb2a960f7, b679c1cffb2f3d0854b8b05ea9e909ad6489046f 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 0.31% 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 acd5931d5adf12f0163f83dc00320e7011f4da92 or a5afc00280986063f1c355821544fabbb2a960f7 or b679c1cffb2f3d0854b8b05ea9e909ad6489046f or 2aa1789880fa5e41049b0f6a74a4fc2fa1997610, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | c71420db653aba30a234d1e4cf86dde376e604fa up to, but not including, acd5931d5adf12f0163f83dc00320e7011f4da92; c71420db653aba30a234d1e4cf86dde376e604fa up to, but not including, a5afc00280986063f1c355821544fabbb2a960f7; c71420db653aba30a234d1e4cf86dde376e604fa up to, but not including, b679c1cffb2f3d0854b8b05ea9e909ad6489046f; c71420db653aba30a234d1e4cf86dde376e604fa up to, but not including, 2aa1789880fa5e41049b0f6a74a4fc2fa1997610; c71420db653aba30a234d1e4cf86dde376e604fa up to, but not including, a03fceae0c65b31ce31840dac5e26684ceecb65b; c71420db653aba30a234d1e4cf86dde376e604fa up to, but not including, aa2eb62525188269cdd402a583b9a8ed94657ff0; 6.0 | acd5931d5adf12f0163f83dc00320e7011f4da92, a5afc00280986063f1c355821544fabbb2a960f7, b679c1cffb2f3d0854b8b05ea9e909ad6489046f, 2aa1789880fa5e41049b0f6a74a4fc2fa1997610, a03fceae0c65b31ce31840dac5e26684ceecb65b, aa2eb62525188269cdd402a583b9a8ed94657ff0 |
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
- AdjacentThe attacker must be on the same local network segment.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- 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:A/AC:L/PR:N/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: wifi: mac80211: defer link RX stats percpu free to RCU sta_remove_link() frees a removed MLO link's RX stats percpu buffer right away, but defers only the link container to RCU: sta_info_free_link(&alloc->info); kfree_rcu(alloc, rcu_head); The RX fast path reads link_sta under rcu_read_lock and writes the percpu stats. A reader that resolved link_sta before the removal keeps the pointer. The container stays alive from the kfree_rcu, so the read still works. But the percpu block it points to is already freed. This needs uses_rss. That is when pcpu_rx_stats exists. The full STA teardown frees the deflink stats only after synchronize_net(). The link removal path had no such barrier. The race is hard to win in practice, but the free should still wait for RCU. Free the link together with its data from a single RCU callback, so the percpu block is reclaimed only after readers drain.
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
- git.kernel.org/stable/c/2aa1789880fa5e41049b0f6a74a4fc2fa1997610
- git.kernel.org/stable/c/a03fceae0c65b31ce31840dac5e26684ceecb65b
- git.kernel.org/stable/c/a5afc00280986063f1c355821544fabbb2a960f7
- git.kernel.org/stable/c/aa2eb62525188269cdd402a583b9a8ed94657ff0
- git.kernel.org/stable/c/acd5931d5adf12f0163f83dc00320e7011f4da92
- git.kernel.org/stable/c/b679c1cffb2f3d0854b8b05ea9e909ad6489046f
Recent Use After Free vulnerabilities
- 7.8 High severity
- 9.8 Critical severity
- 7.5 High severity
- 7.8 High severity
- 7.8 High severity
- 8.8 High severity
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