Linux: Use After Free
CVE-2024-35865 is a critical-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions a710ef9e974f18232d2b9b19c90eda1a1167b2d4, 84488466b7a69570bdbf76dd9576847ab97d54e7, 21fed37d2bdcde33453faf61d3d4d96c355f04bd 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 0.63% chance of exploitation within 30 days, higher than 51% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Linux to a710ef9e974f18232d2b9b19c90eda1a1167b2d4 or 84488466b7a69570bdbf76dd9576847ab97d54e7 or 21fed37d2bdcde33453faf61d3d4d96c355f04bd or 3dba0e5276f131e36d6d8043191d856f49238628, 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.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 7f48558e6489d032b1584b0cc9ac4bb11072c034 up to, but not including, a710ef9e974f18232d2b9b19c90eda1a1167b2d4; 7f48558e6489d032b1584b0cc9ac4bb11072c034 up to, but not including, 84488466b7a69570bdbf76dd9576847ab97d54e7; 7f48558e6489d032b1584b0cc9ac4bb11072c034 up to, but not including, 21fed37d2bdcde33453faf61d3d4d96c355f04bd; 7f48558e6489d032b1584b0cc9ac4bb11072c034 up to, but not including, 3dba0e5276f131e36d6d8043191d856f49238628; 7f48558e6489d032b1584b0cc9ac4bb11072c034 up to, but not including, 22863485a4626ec6ecf297f4cc0aef709bc862e4; a67172a013953664b1dad03c648200c70b90506c; 3.12.48 up to, but not including, 3.13; 3.13 | a710ef9e974f18232d2b9b19c90eda1a1167b2d4, 84488466b7a69570bdbf76dd9576847ab97d54e7, 21fed37d2bdcde33453faf61d3d4d96c355f04bd, 3dba0e5276f131e36d6d8043191d856f49238628, 22863485a4626ec6ecf297f4cc0aef709bc862e4, 3.13 |
| Linux | Linux Kernel | before 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
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- 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:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.8 | Critical | CNA |
| CVSS 3.1 | 5.5 | Medium | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix potential UAF in smb2_is_valid_oplock_break() 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
Other references
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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