Linux: Double Free
CVE-2026-23408 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 c6347a2116ecccb8fd9ee4ebc75ae41d1d7ef689, c053ae381ce227577567d1ef10090ce7506d7a28, 35f4caec1352054b9a61cfdf2bf1898073637aa0 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 0.18% 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 c6347a2116ecccb8fd9ee4ebc75ae41d1d7ef689 or c053ae381ce227577567d1ef10090ce7506d7a28 or 35f4caec1352054b9a61cfdf2bf1898073637aa0 or 55ef2af7490aaf72f8ffe11ec44c6bcb7eb2162a, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.253 or 5.15.203 or 6.1.169 or 6.6.130, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 145a0ef21c8e944957f58e2c8ffcd8a10f46266a up to, but not including, c6347a2116ecccb8fd9ee4ebc75ae41d1d7ef689; 145a0ef21c8e944957f58e2c8ffcd8a10f46266a up to, but not including, c053ae381ce227577567d1ef10090ce7506d7a28; 145a0ef21c8e944957f58e2c8ffcd8a10f46266a up to, but not including, 35f4caec1352054b9a61cfdf2bf1898073637aa0; 145a0ef21c8e944957f58e2c8ffcd8a10f46266a up to, but not including, 55ef2af7490aaf72f8ffe11ec44c6bcb7eb2162a; 145a0ef21c8e944957f58e2c8ffcd8a10f46266a up to, but not including, 86feeccd6b93ed94bd6655f30de80f163f8d5a45; 145a0ef21c8e944957f58e2c8ffcd8a10f46266a up to, but not including, 7998ab3010d2317643f91828f1853d954ef31387; 145a0ef21c8e944957f58e2c8ffcd8a10f46266a up to, but not including, 18b5233e860c294a847ee07869d93c0b8673a54b; 145a0ef21c8e944957f58e2c8ffcd8a10f46266a up to, but not including, 5df0c44e8f5f619d3beb871207aded7c78414502; and 1 more ranges | c6347a2116ecccb8fd9ee4ebc75ae41d1d7ef689, c053ae381ce227577567d1ef10090ce7506d7a28, 35f4caec1352054b9a61cfdf2bf1898073637aa0, 55ef2af7490aaf72f8ffe11ec44c6bcb7eb2162a, 86feeccd6b93ed94bd6655f30de80f163f8d5a45, 7998ab3010d2317643f91828f1853d954ef31387 |
| Linux | Linux Kernel | 5.5.1 up to, but not including, 5.10.253; 5.11 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.169; 6.2 up to, but not including, 6.6.130; 6.7 up to, but not including, 6.12.77; 6.13 up to, but not including, 6.18.18; 6.19 up to, but not including, 6.19.8; 5.5; and 1 more ranges | 5.10.253, 5.15.203, 6.1.169, 6.6.130, 6.12.77, 6.18.18 |
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 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: apparmor: Fix double free of ns_name in aa_replace_profiles() if ns_name is NULL after 1071 error = aa_unpack(udata, &lh, &ns_name); and if ent->ns_name contains an ns_name in 1089 } else if (ent->ns_name) { then ns_name is assigned the ent->ns_name 1095 ns_name = ent->ns_name; however ent->ns_name is freed at 1262 aa_load_ent_free(ent); and then again when freeing ns_name at 1270 kfree(ns_name); Fix this by NULLing out ent->ns_name after it is transferred to ns_name ")
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/18b5233e860c294a847ee07869d93c0b8673a54b
- git.kernel.org/stable/c/35f4caec1352054b9a61cfdf2bf1898073637aa0
- git.kernel.org/stable/c/55ef2af7490aaf72f8ffe11ec44c6bcb7eb2162a
- git.kernel.org/stable/c/5df0c44e8f5f619d3beb871207aded7c78414502
- git.kernel.org/stable/c/7998ab3010d2317643f91828f1853d954ef31387
- git.kernel.org/stable/c/86feeccd6b93ed94bd6655f30de80f163f8d5a45
- git.kernel.org/stable/c/c053ae381ce227577567d1ef10090ce7506d7a28
- git.kernel.org/stable/c/c6347a2116ecccb8fd9ee4ebc75ae41d1d7ef689
Recent Double Free vulnerabilities
- 7.8 High severity
- 7.5 High severity
- 7.0 High severity
- 7.5 High severity
- 7.8 High severity
- 7.8 High severity
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