Linux: Use After Free
CVE-2024-46845 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 8c72f0b2c45f21cb8b00fc37f79f632d7e46c2ed, 8a9d0d405159e9c796ddf771f7cff691c1a2bc1e, e6a53481da292d970d1edf0d8831121d1c5e2f0d 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 0.24% 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 8c72f0b2c45f21cb8b00fc37f79f632d7e46c2ed or 8a9d0d405159e9c796ddf771f7cff691c1a2bc1e or e6a53481da292d970d1edf0d8831121d1c5e2f0d, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.51 or 6.10.10, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | e88ed227f639ebcb31ed4e5b88756b47d904584b up to, but not including, 8c72f0b2c45f21cb8b00fc37f79f632d7e46c2ed; e88ed227f639ebcb31ed4e5b88756b47d904584b up to, but not including, 8a9d0d405159e9c796ddf771f7cff691c1a2bc1e; e88ed227f639ebcb31ed4e5b88756b47d904584b up to, but not including, e6a53481da292d970d1edf0d8831121d1c5e2f0d; 6.5 | 8c72f0b2c45f21cb8b00fc37f79f632d7e46c2ed, 8a9d0d405159e9c796ddf771f7cff691c1a2bc1e, e6a53481da292d970d1edf0d8831121d1c5e2f0d |
| Linux | Linux Kernel | 6.5 up to, but not including, 6.6.51; 6.7 up to, but not including, 6.10.10; 6.11 | 6.6.51, 6.10.10 |
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 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: tracing/timerlat: Only clear timer if a kthread exists The timerlat tracer can use user space threads to check for osnoise and timer latency. If the program using this is killed via a SIGTERM, the threads are shutdown one at a time and another tracing instance can start up resetting the threads before they are fully closed. That causes the hrtimer assigned to the kthread to be shutdown and freed twice when the dying thread finally closes the file descriptors, causing a use-after-free bug. Only cancel the hrtimer if the associated thread is still around. Also add the interface_lock around the resetting of the tlat_var->kthread. Note, this is just a quick fix that can be backported to stable. A real fix is to have a better synchronization between the shutdown of old threads and the starting of new ones.
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
- 7.0 High severity
- 7.8 High severity
- 7.8 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
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