Linux: Use After Free
CVE-2024-35861 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 7e8360ac8774e19b0b25f44fff84a105bb2417e4, 2cfff21732132e363b4cc275d63ea98f1af726c1, f9a96a7ad1e8d25dc6662bc7552e0752de74a20d 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 0.66% chance of exploitation within 30 days, higher than 52% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 7e8360ac8774e19b0b25f44fff84a105bb2417e4 or 2cfff21732132e363b4cc275d63ea98f1af726c1 or f9a96a7ad1e8d25dc6662bc7552e0752de74a20d or e0e50401cc3921c9eaf1b0e667db174519ea939f, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.85 or 6.6.26 or 6.8.5, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | dca65818c80cf06e0f08ba2cf94060a5236e73c2 up to, but not including, 7e8360ac8774e19b0b25f44fff84a105bb2417e4; dca65818c80cf06e0f08ba2cf94060a5236e73c2 up to, but not including, 2cfff21732132e363b4cc275d63ea98f1af726c1; dca65818c80cf06e0f08ba2cf94060a5236e73c2 up to, but not including, f9a96a7ad1e8d25dc6662bc7552e0752de74a20d; dca65818c80cf06e0f08ba2cf94060a5236e73c2 up to, but not including, e0e50401cc3921c9eaf1b0e667db174519ea939f; dd9ccff8c8980bf9ea7f25e83eeb28154f902920; 5.17.2 up to, but not including, 5.18; 5.18 | 7e8360ac8774e19b0b25f44fff84a105bb2417e4, 2cfff21732132e363b4cc275d63ea98f1af726c1, f9a96a7ad1e8d25dc6662bc7552e0752de74a20d, e0e50401cc3921c9eaf1b0e667db174519ea939f, 5.18 |
| Linux | Linux Kernel | 5.17.2 up to, but not including, 6.1.85; 6.2 up to, but not including, 6.6.26; 6.7 up to, but not including, 6.8.5; 6.9 | 6.1.85, 6.6.26, 6.8.5 |
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: client: fix potential UAF in cifs_signal_cifsd_for_reconnect() Skip sessions that are being teared down (status == SES_EXITING) to avoid UAF.
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
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.8 High severity
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