Linux: Use After Free
CVE-2026-68391 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 84674dd1d3192ecb050827d3148642609c0c9dbb, b56f2ecafc08f372bf0529f9c4f3f429cb1702dc, f915e74b6f18293d1d69a2a3305ef321ff7c0172 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 0.13% 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 84674dd1d3192ecb050827d3148642609c0c9dbb or b56f2ecafc08f372bf0529f9c4f3f429cb1702dc or f915e74b6f18293d1d69a2a3305ef321ff7c0172 or d5b3b484b62bb0f4542e7622789d28871626cdf0, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 7b445e220db9a2c58be5d09bbbd322abf1b1452a up to, but not including, 84674dd1d3192ecb050827d3148642609c0c9dbb; 7b445e220db9a2c58be5d09bbbd322abf1b1452a up to, but not including, b56f2ecafc08f372bf0529f9c4f3f429cb1702dc; 7b445e220db9a2c58be5d09bbbd322abf1b1452a up to, but not including, f915e74b6f18293d1d69a2a3305ef321ff7c0172; 7b445e220db9a2c58be5d09bbbd322abf1b1452a up to, but not including, d5b3b484b62bb0f4542e7622789d28871626cdf0; 7b445e220db9a2c58be5d09bbbd322abf1b1452a up to, but not including, ecdcb55ea1c01dda074406f38058785a69526734; 7b445e220db9a2c58be5d09bbbd322abf1b1452a up to, but not including, da55f570191d5d72f10c607a7043b947eb05ea46; 6.0 | 84674dd1d3192ecb050827d3148642609c0c9dbb, b56f2ecafc08f372bf0529f9c4f3f429cb1702dc, f915e74b6f18293d1d69a2a3305ef321ff7c0172, d5b3b484b62bb0f4542e7622789d28871626cdf0, ecdcb55ea1c01dda074406f38058785a69526734, da55f570191d5d72f10c607a7043b947eb05ea46 |
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: Bluetooth: mgmt: hold reference for hci_conn in mgmt_pending_cmds Dereferencing RCU-protected pointers outside critical sections is invalid and may lead to UAF. Use of hci_conn in hci_sync callbacks also needs to hold refcount to avoid UAF. Take appropriate locks for hci_conn lookups, and take refcount for hci_conn pointers stored in mgmt_pending_cmd so that the pointer stays valid. When accessing conn->state, ensure hdev->lock is held to avoid data race.
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/84674dd1d3192ecb050827d3148642609c0c9dbb
- git.kernel.org/stable/c/b56f2ecafc08f372bf0529f9c4f3f429cb1702dc
- git.kernel.org/stable/c/d5b3b484b62bb0f4542e7622789d28871626cdf0
- git.kernel.org/stable/c/da55f570191d5d72f10c607a7043b947eb05ea46
- git.kernel.org/stable/c/ecdcb55ea1c01dda074406f38058785a69526734
- git.kernel.org/stable/c/f915e74b6f18293d1d69a2a3305ef321ff7c0172
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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