Linux: Use After Free
CVE-2024-26856 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 e46274df1100fb0c06704195bfff5bfbd418bf64, 0de693d68b0a18d5e256556c7c62d92cca35ad52, e83bebb718fd1f42549358730e1206164e0861d6 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 0.32% 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 e46274df1100fb0c06704195bfff5bfbd418bf64 or 0de693d68b0a18d5e256556c7c62d92cca35ad52 or e83bebb718fd1f42549358730e1206164e0861d6 or 71809805b95052ff551922f11660008fb3666025, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.152 or 6.1.82 or 6.6.22 or 6.7.10, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | b37a1bae742f92cc9b1f777d54e04ee3d86bbfc2 up to, but not including, e46274df1100fb0c06704195bfff5bfbd418bf64; b37a1bae742f92cc9b1f777d54e04ee3d86bbfc2 up to, but not including, 0de693d68b0a18d5e256556c7c62d92cca35ad52; b37a1bae742f92cc9b1f777d54e04ee3d86bbfc2 up to, but not including, e83bebb718fd1f42549358730e1206164e0861d6; b37a1bae742f92cc9b1f777d54e04ee3d86bbfc2 up to, but not including, 71809805b95052ff551922f11660008fb3666025; b37a1bae742f92cc9b1f777d54e04ee3d86bbfc2 up to, but not including, 89d72d4125e94aa3c2140fedd97ce07ba9e37674; 5.14 | e46274df1100fb0c06704195bfff5bfbd418bf64, 0de693d68b0a18d5e256556c7c62d92cca35ad52, e83bebb718fd1f42549358730e1206164e0861d6, 71809805b95052ff551922f11660008fb3666025, 89d72d4125e94aa3c2140fedd97ce07ba9e37674 |
| Linux | Linux Kernel | 5.14 up to, but not including, 5.15.152; 5.16 up to, but not including, 6.1.82; 6.2 up to, but not including, 6.6.22; 6.7 up to, but not including, 6.7.10; 6.8 | 5.15.152, 6.1.82, 6.6.22, 6.7.10 |
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: net: sparx5: Fix use after free inside sparx5_del_mact_entry Based on the static analyzis of the code it looks like when an entry from the MAC table was removed, the entry was still used after being freed. More precise the vid of the mac_entry was used after calling devm_kfree on the mac_entry. The fix consists in first using the vid of the mac_entry to delete the entry from the HW and after that to free it.
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: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/0de693d68b0a18d5e256556c7c62d92cca35ad52Mailing List
- git.kernel.org/stable/c/71809805b95052ff551922f11660008fb3666025Mailing List
- git.kernel.org/stable/c/89d72d4125e94aa3c2140fedd97ce07ba9e37674Mailing List
- git.kernel.org/stable/c/e46274df1100fb0c06704195bfff5bfbd418bf64Mailing List
- git.kernel.org/stable/c/e83bebb718fd1f42549358730e1206164e0861d6Mailing List
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.0 High severity
- 7.8 High severity
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