Linux: Use After Free
CVE-2024-26630 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.1 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 ba60fdf75e89ea762bb617be578dc47f27655117, fe7e008e0ce728252e4ec652cceebcc62211657c, 3a75cb05d53f4a6823a32deb078de1366954a804 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 0.3% 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 ba60fdf75e89ea762bb617be578dc47f27655117 or fe7e008e0ce728252e4ec652cceebcc62211657c or 3a75cb05d53f4a6823a32deb078de1366954a804, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.21 or 6.7.9, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | cf264e1329fb0307e044f7675849f9f38b44c11a up to, but not including, ba60fdf75e89ea762bb617be578dc47f27655117; cf264e1329fb0307e044f7675849f9f38b44c11a up to, but not including, fe7e008e0ce728252e4ec652cceebcc62211657c; cf264e1329fb0307e044f7675849f9f38b44c11a up to, but not including, 3a75cb05d53f4a6823a32deb078de1366954a804; 6.5 | ba60fdf75e89ea762bb617be578dc47f27655117, fe7e008e0ce728252e4ec652cceebcc62211657c, 3a75cb05d53f4a6823a32deb078de1366954a804 |
| Linux | Linux Kernel | 6.5 up to, but not including, 6.6.21; 6.7 up to, but not including, 6.7.9; 6.8 | 6.6.21, 6.7.9 |
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
- NoneNothing can be modified.
- 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:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.1 | High | CNA |
| CVSS 3.1 | 7.1 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: mm: cachestat: fix folio read-after-free in cache walk In cachestat, we access the folio from the page cache's xarray to compute its page offset, and check for its dirty and writeback flags. However, we do not hold a reference to the folio before performing these actions, which means the folio can concurrently be released and reused as another folio/page/slab. Get around this altogether by just using xarray's existing machinery for the folio page offsets and dirty/writeback states. This changes behavior for tmpfs files to now always report zeroes in their dirty and writeback counters. This is okay as tmpfs doesn't follow conventional writeback cache behavior: its pages get "cleaned" during swapout, after which they're no longer resident etc.
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
- 8.8 High severity
- 7.8 High severity
- 8.4 High severity
- 8.4 High severity
- 8.4 High severity
- 7.8 High severity
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