Linux: Double Free
CVE-2024-40940 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 531eab2da27dd42d68dfb841d82e987f4a6738b8, d857df86837ac1c30592e8a068204d16feac9930, a03a3fa12769e25f4385bee587afe1445aee7f7a 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 0.26% 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 531eab2da27dd42d68dfb841d82e987f4a6738b8 or d857df86837ac1c30592e8a068204d16feac9930 or a03a3fa12769e25f4385bee587afe1445aee7f7a or 229bedbf62b13af5aba6525ad10b62ad38d9ccb5, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.95 or 6.6.35 or 6.9.6, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 352899f384d4aefa77ede6310d08c1b515612a8f up to, but not including, 531eab2da27dd42d68dfb841d82e987f4a6738b8; 352899f384d4aefa77ede6310d08c1b515612a8f up to, but not including, d857df86837ac1c30592e8a068204d16feac9930; 352899f384d4aefa77ede6310d08c1b515612a8f up to, but not including, a03a3fa12769e25f4385bee587afe1445aee7f7a; 352899f384d4aefa77ede6310d08c1b515612a8f up to, but not including, 229bedbf62b13af5aba6525ad10b62ad38d9ccb5; 5.19 | 531eab2da27dd42d68dfb841d82e987f4a6738b8, d857df86837ac1c30592e8a068204d16feac9930, a03a3fa12769e25f4385bee587afe1445aee7f7a, 229bedbf62b13af5aba6525ad10b62ad38d9ccb5 |
| Linux | Linux Kernel | 5.19 up to, but not including, 6.1.95; 6.2 up to, but not including, 6.6.35; 6.7 up to, but not including, 6.9.6; 6.10 | 6.1.95, 6.6.35, 6.9.6 |
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.
Official description
In the Linux kernel, the following vulnerability has been resolved: net/mlx5: Fix tainted pointer delete is case of flow rules creation fail In case of flow rule creation fail in mlx5_lag_create_port_sel_table(), instead of previously created rules, the tainted pointer is deleted deveral times. Fix this bug by using correct flow rules pointers. Found by Linux Verification Center (linuxtesting.org) with SVACE.
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.
- 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 Double Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.1 High severity
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