Linux: Double Free
CVE-2026-23098 is a high-severity double 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 25aab6bfc31017a7e52035b99aef5c2b6bde8ffb, 6e0110ea90313b7c0558a0b77038274a6821caf8, 7c48fdf2d1349bb54815b56fb012b9d577707708 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 0.2% 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 25aab6bfc31017a7e52035b99aef5c2b6bde8ffb or 6e0110ea90313b7c0558a0b77038274a6821caf8 or 7c48fdf2d1349bb54815b56fb012b9d577707708 or bd8955337e3764f912f49b360e176d8aaecf7016, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.249 or 5.15.199 or 6.1.162 or 6.6.122, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 25aab6bfc31017a7e52035b99aef5c2b6bde8ffb; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 6e0110ea90313b7c0558a0b77038274a6821caf8; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 7c48fdf2d1349bb54815b56fb012b9d577707708; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, bd8955337e3764f912f49b360e176d8aaecf7016; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 94d1a8bd08af1f4cc345c5c29f5db1ea72b8bb8c; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 9f5fa78d9980fe75a69835521627ab7943cb3d67; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, ba1096c315283ee3292765f6aea4cca15816c4f7; 2.6.12 | 25aab6bfc31017a7e52035b99aef5c2b6bde8ffb, 6e0110ea90313b7c0558a0b77038274a6821caf8, 7c48fdf2d1349bb54815b56fb012b9d577707708, bd8955337e3764f912f49b360e176d8aaecf7016, 94d1a8bd08af1f4cc345c5c29f5db1ea72b8bb8c, 9f5fa78d9980fe75a69835521627ab7943cb3d67 |
| Linux | Linux Kernel | 2.6.12.1 up to, but not including, 5.10.249; 5.11 up to, but not including, 5.15.199; 5.16 up to, but not including, 6.1.162; 6.2 up to, but not including, 6.6.122; 6.7 up to, but not including, 6.12.68; 6.13 up to, but not including, 6.18.8; 2.6.12; 6.19 | 5.10.249, 5.15.199, 6.1.162, 6.6.122, 6.12.68, 6.18.8 |
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: netrom: fix double-free in nr_route_frame() In nr_route_frame(), old_skb is immediately freed without checking if nr_neigh->ax25 pointer is NULL. Therefore, if nr_neigh->ax25 is NULL, the caller function will free old_skb again, causing a double-free bug. Therefore, to prevent this, we need to modify it to check whether nr_neigh->ax25 is NULL before freeing old_skb.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Double Free
The product calls free() twice on the same memory address.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
- Use a static analysis tool to find double free instances.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/25aab6bfc31017a7e52035b99aef5c2b6bde8ffb
- git.kernel.org/stable/c/6e0110ea90313b7c0558a0b77038274a6821caf8
- git.kernel.org/stable/c/7c48fdf2d1349bb54815b56fb012b9d577707708
- git.kernel.org/stable/c/94d1a8bd08af1f4cc345c5c29f5db1ea72b8bb8c
- git.kernel.org/stable/c/9f5fa78d9980fe75a69835521627ab7943cb3d67
- git.kernel.org/stable/c/ba1096c315283ee3292765f6aea4cca15816c4f7
- git.kernel.org/stable/c/bd8955337e3764f912f49b360e176d8aaecf7016
Recent Double Free vulnerabilities
- 7.8 High severity
- 7.5 High severity
- 7.8 High severity
- 7.5 High severity
- 7.0 High severity
- 7.8 High severity
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