Linux: Use After Free
CVE-2026-68178 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 1996639f824ce9468395cdb7bcb8f467fa787e77, 1da310b94504d42001e9c32c43c5dc105b777e5f, 9e9a82d00c3d10129fc310a7547b24a679d5d920 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 1996639f824ce9468395cdb7bcb8f467fa787e77 or 1da310b94504d42001e9c32c43c5dc105b777e5f or 9e9a82d00c3d10129fc310a7547b24a679d5d920 or 3b231f1e9990f4c21220d0a69733ce2105891ff9, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | b9873755a6c8ccfce79094c4dce9efa3ecb1a749 up to, but not including, 1996639f824ce9468395cdb7bcb8f467fa787e77; b9873755a6c8ccfce79094c4dce9efa3ecb1a749 up to, but not including, 1da310b94504d42001e9c32c43c5dc105b777e5f; b9873755a6c8ccfce79094c4dce9efa3ecb1a749 up to, but not including, 9e9a82d00c3d10129fc310a7547b24a679d5d920; b9873755a6c8ccfce79094c4dce9efa3ecb1a749 up to, but not including, 3b231f1e9990f4c21220d0a69733ce2105891ff9; 6.8 | 1996639f824ce9468395cdb7bcb8f467fa787e77, 1da310b94504d42001e9c32c43c5dc105b777e5f, 9e9a82d00c3d10129fc310a7547b24a679d5d920, 3b231f1e9990f4c21220d0a69733ce2105891ff9 |
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: misc: nsm: pin the module while the device is open misc_open() installs a misc driver's file operations with fops_get(), which pins file_operations::owner before replacing the file's f_op. The NSM misc device leaves nsm_dev_fops.owner unset, so opening /dev/nsm does not take a module reference on the nsm driver. If the driver is built as a module, an open file descriptor can therefore survive rmmod of the module that provides its ioctl callbacks. A later ioctl through that descriptor can call into unloaded module text. Set nsm_dev_fops.owner to THIS_MODULE so the misc core holds the module while any /dev/nsm file descriptor is open, matching the lifetime expectation for the installed file operations.
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
Spotted an error? Tell us.