Linux: Use After Free
CVE-2026-68393 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 3f98e7f38e1bb761a9964a8851f9c08e9c23b3dd, 83b7e67698d0b93f685875ce82c8d335436834f7, 38326774df6198df0cc2744cc73bf77cb741c538 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 0.24% 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 3f98e7f38e1bb761a9964a8851f9c08e9c23b3dd or 83b7e67698d0b93f685875ce82c8d335436834f7 or 38326774df6198df0cc2744cc73bf77cb741c538 or d5efd6e4b8b0634af6843178fe1a7dd2b2178a3d, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | eb8b860e87b296bd1874c79a668081efd00f9754 up to, but not including, 3f98e7f38e1bb761a9964a8851f9c08e9c23b3dd; 6d0417e4e1cf66fd917f06f0454958362714ef7d up to, but not including, 83b7e67698d0b93f685875ce82c8d335436834f7; 6d0417e4e1cf66fd917f06f0454958362714ef7d up to, but not including, 38326774df6198df0cc2744cc73bf77cb741c538; 6d0417e4e1cf66fd917f06f0454958362714ef7d up to, but not including, d5efd6e4b8b0634af6843178fe1a7dd2b2178a3d; 94bf6380e936339a700c0b3171a49baf512aa70b; 6.12.28 up to, but not including, 6.12.114; 6.14.6 up to, but not including, 6.15; 6.15 | 3f98e7f38e1bb761a9964a8851f9c08e9c23b3dd, 83b7e67698d0b93f685875ce82c8d335436834f7, 38326774df6198df0cc2744cc73bf77cb741c538, d5efd6e4b8b0634af6843178fe1a7dd2b2178a3d, 6.12.114, 6.15 |
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: Bluetooth: hci_sync: extend conn_hash lookup critical sections Using RCU-protected pointers outside the critical sections without refcount is incorrect and may result to UAF. Extend critical section to cover both hci_conn_hash lookup and use of the returned conn. Add surrounding rcu_read_lock() also when return value is not used, in preparation for RCU lockdep requirement to hci_lookup_le_connect(). This avoids concurrent deletion of the conn before we are done dereferencing it. Also, make sure to hold hdev->lock when accessing hdev->accept_list.
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
- 7.8 High severity
- 9.8 Critical severity
- 7.5 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
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