Linux: Use After Free
CVE-2024-56675 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 9245459a992d22fe0e92e988f49db1fec82c184a, f9f85df30118f3f4112761e6682fc60ebcce23e5, 9b53d2c2a38a1effc341d99be3f99fa7ef17047d 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 0.23% 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 9245459a992d22fe0e92e988f49db1fec82c184a or f9f85df30118f3f4112761e6682fc60ebcce23e5 or 9b53d2c2a38a1effc341d99be3f99fa7ef17047d or ef1b808e3b7c98612feceedf985c2fbbeb28f956, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.121 or 6.6.67 or 6.12.6, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 8c7dcb84e3b744b2b70baa7a44a9b1881c33a9c9 up to, but not including, 9245459a992d22fe0e92e988f49db1fec82c184a; 8c7dcb84e3b744b2b70baa7a44a9b1881c33a9c9 up to, but not including, f9f85df30118f3f4112761e6682fc60ebcce23e5; 8c7dcb84e3b744b2b70baa7a44a9b1881c33a9c9 up to, but not including, 9b53d2c2a38a1effc341d99be3f99fa7ef17047d; 8c7dcb84e3b744b2b70baa7a44a9b1881c33a9c9 up to, but not including, ef1b808e3b7c98612feceedf985c2fbbeb28f956; 6.0 | 9245459a992d22fe0e92e988f49db1fec82c184a, f9f85df30118f3f4112761e6682fc60ebcce23e5, 9b53d2c2a38a1effc341d99be3f99fa7ef17047d, ef1b808e3b7c98612feceedf985c2fbbeb28f956 |
| Linux | Linux Kernel | 6.0 up to, but not including, 6.1.121; 6.2 up to, but not including, 6.6.67; 6.7 up to, but not including, 6.12.6; 6.13 | 6.1.121, 6.6.67, 6.12.6 |
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.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | NVD |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix UAF via mismatching bpf_prog/attachment RCU flavors Uprobes always use bpf_prog_run_array_uprobe() under tasks-trace-RCU protection. But it is possible to attach a non-sleepable BPF program to a uprobe, and non-sleepable BPF programs are freed via normal RCU (see __bpf_prog_put_noref()). This leads to UAF of the bpf_prog because a normal RCU grace period does not imply a tasks-trace-RCU grace period. Fix it by explicitly waiting for a tasks-trace-RCU grace period after removing the attachment of a bpf_prog to a perf_event.
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
Other references
Recent Use After Free vulnerabilities
- 7.0 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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