Linux: Use After Free
CVE-2026-23226 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 c00f3938f7ac52770907768e440cf253af9cbb63, 43ad494ac6e940a8eabf25d5bd77bb3bb53b1153, 4c2ca31608521895dd742a43beca4b4d29762345 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 0.5% 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 c00f3938f7ac52770907768e440cf253af9cbb63 or 43ad494ac6e940a8eabf25d5bd77bb3bb53b1153 or 4c2ca31608521895dd742a43beca4b4d29762345 or e4a8a96a93d08570e0405cfd989a8a07e5b6ff33, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.18.11 or 6.19.1, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 91bbf9cb2387a0d76322e9a343bc6bc160f66b3f up to, but not including, c00f3938f7ac52770907768e440cf253af9cbb63; 1d9c4172110e645b383ff13eee759728d74f1a5d up to, but not including, 43ad494ac6e940a8eabf25d5bd77bb3bb53b1153; 1d9c4172110e645b383ff13eee759728d74f1a5d up to, but not including, 4c2ca31608521895dd742a43beca4b4d29762345; 1d9c4172110e645b383ff13eee759728d74f1a5d up to, but not including, e4a8a96a93d08570e0405cfd989a8a07e5b6ff33; 1d9c4172110e645b383ff13eee759728d74f1a5d up to, but not including, 36ef605c0395b94b826a8c8d6f2697071173de6e; 1d9c4172110e645b383ff13eee759728d74f1a5d up to, but not including, 4f3a06cc57976cafa8c6f716646be6c79a99e485; b1caecbf34b8c8260d851ec4efde71f3694460b7; 853c416710b075153c1e1421e099ffbe5dac68ce; and 4 more ranges | c00f3938f7ac52770907768e440cf253af9cbb63, 43ad494ac6e940a8eabf25d5bd77bb3bb53b1153, 4c2ca31608521895dd742a43beca4b4d29762345, e4a8a96a93d08570e0405cfd989a8a07e5b6ff33, 36ef605c0395b94b826a8c8d6f2697071173de6e, 4f3a06cc57976cafa8c6f716646be6c79a99e485 |
| Linux | Linux Kernel | 6.3 up to, but not including, 6.18.11; 6.19 up to, but not including, 6.19.1 | 6.18.11, 6.19.1 |
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 NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: add chann_lock to protect ksmbd_chann_list xarray ksmbd_chann_list xarray lacks synchronization, allowing use-after-free in multi-channel sessions (between lookup_chann_list() and ksmbd_chann_del). Adds rw_semaphore chann_lock to struct ksmbd_session and protects all xa_load/xa_store/xa_erase accesses.
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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
Spotted an error? Tell us.