Linux: Use After Free
CVE-2024-35869 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 645f332c6b63499cc76197f9b6bffcc659ba64cc, e1db9ae87b7148c021daee1fcc4bc71b2ac58a79, 062a7f0ff46eb57aff526897bd2bebfdb1d3046a 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 0.65% chance of exploitation within 30 days, higher than 52% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Linux to 645f332c6b63499cc76197f9b6bffcc659ba64cc or e1db9ae87b7148c021daee1fcc4bc71b2ac58a79 or 062a7f0ff46eb57aff526897bd2bebfdb1d3046a or 6.3, whichever matches your release line, or a later version.
- Update linux_kernel to 645f332c6b63 or e1db9ae87b71 or 062a7f0ff46e, 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 | 8e3554150d6c80a84b3cb046615d1a0e943811dc up to, but not including, 645f332c6b63499cc76197f9b6bffcc659ba64cc; 8e3554150d6c80a84b3cb046615d1a0e943811dc up to, but not including, e1db9ae87b7148c021daee1fcc4bc71b2ac58a79; 8e3554150d6c80a84b3cb046615d1a0e943811dc up to, but not including, 062a7f0ff46eb57aff526897bd2bebfdb1d3046a; f30d226bcc9f0e2d97b4a6e94c43a28148fbeab6; c082c3be0f96e759ff2e361d929832fda0b93851; 6.2.15 up to, but not including, 6.3; 6.3.2 up to, but not including, 6.4; 6.4 | 645f332c6b63499cc76197f9b6bffcc659ba64cc, e1db9ae87b7148c021daee1fcc4bc71b2ac58a79, 062a7f0ff46eb57aff526897bd2bebfdb1d3046a, 6.3, 6.4 |
| Linux | linux_kernel | 1da177e4c3f4 up to, but not including, 645f332c6b63; 1da177e4c3f4 up to, but not including, e1db9ae87b71; 1da177e4c3f4 up to, but not including, 062a7f0ff46e | 645f332c6b63, e1db9ae87b71, 062a7f0ff46e |
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 | 8.4 | High | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: smb: client: guarantee refcounted children from parent session Avoid potential use-after-free bugs when walking DFS referrals, mounting and performing DFS failover by ensuring that all children from parent @tcon->ses are also refcounted. They're all needed across the entire DFS mount. Get rid of @tcon->dfs_ses_list while we're at it, too.
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: total).
- 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
- 7.8 High severity
- 7.8 High severity
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