Linux: Use After Free
CVE-2026-43378 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 e1b21e6066615e7d3d3a7aa2677e415e563fd7cc, b720c84087cb547f23ce03eab93568c1769e4556, 54b48ae83de8bb06e65079d96368efe359d4909c 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 e1b21e6066615e7d3d3a7aa2677e415e563fd7cc or b720c84087cb547f23ce03eab93568c1769e4556 or 54b48ae83de8bb06e65079d96368efe359d4909c or 8f5b1a7cb009a93c48e9e334a2f59a660f9afc07, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.167 or 6.6.130 or 6.12.78 or 6.18.19, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 up to, but not including, e1b21e6066615e7d3d3a7aa2677e415e563fd7cc; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 up to, but not including, b720c84087cb547f23ce03eab93568c1769e4556; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 up to, but not including, 54b48ae83de8bb06e65079d96368efe359d4909c; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 up to, but not including, 8f5b1a7cb009a93c48e9e334a2f59a660f9afc07; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 up to, but not including, 190e5f808e8058640b408ccfed25440b441a718a; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 up to, but not including, 1e689a56173827669a35da7cb2a3c78ed5c53680; 5.15 | e1b21e6066615e7d3d3a7aa2677e415e563fd7cc, b720c84087cb547f23ce03eab93568c1769e4556, 54b48ae83de8bb06e65079d96368efe359d4909c, 8f5b1a7cb009a93c48e9e334a2f59a660f9afc07, 190e5f808e8058640b408ccfed25440b441a718a, 1e689a56173827669a35da7cb2a3c78ed5c53680 |
| Linux | Linux Kernel | 5.15 up to, but not including, 6.1.167; 6.2 up to, but not including, 6.6.130; 6.7 up to, but not including, 6.12.78; 6.13 up to, but not including, 6.18.19; 6.19 up to, but not including, 6.19.9; 7.0 | 6.1.167, 6.6.130, 6.12.78, 6.18.19, 6.19.9 |
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 | 9.8 | Critical | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: smb: server: fix use-after-free in smb2_open() The opinfo pointer obtained via rcu_dereference(fp->f_opinfo) is dereferenced after rcu_read_unlock(), creating a use-after-free window.
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
- git.kernel.org/stable/c/190e5f808e8058640b408ccfed25440b441a718a
- git.kernel.org/stable/c/1e689a56173827669a35da7cb2a3c78ed5c53680
- git.kernel.org/stable/c/54b48ae83de8bb06e65079d96368efe359d4909c
- git.kernel.org/stable/c/8f5b1a7cb009a93c48e9e334a2f59a660f9afc07
- git.kernel.org/stable/c/b720c84087cb547f23ce03eab93568c1769e4556
- git.kernel.org/stable/c/e1b21e6066615e7d3d3a7aa2677e415e563fd7cc
Recent Use After Free vulnerabilities
- 7.3 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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