Linux: Use After Free
CVE-2023-52483 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 6c52b12159049046483fdb0c411a0a1869c41a67, 1db0724a01b558feb1ecae551782add1951a114a, 2405f64a95a7a094eb24cba9bcfaffd1ea264de4 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 6c52b12159049046483fdb0c411a0a1869c41a67 or 1db0724a01b558feb1ecae551782add1951a114a or 2405f64a95a7a094eb24cba9bcfaffd1ea264de4 or 5093bbfc10ab6636b32728e35813cbd79feb063c, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.137 or 6.1.59 or 6.5.8, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 889b7da23abf92faf34491df95733bda63639e32 up to, but not including, 6c52b12159049046483fdb0c411a0a1869c41a67; 889b7da23abf92faf34491df95733bda63639e32 up to, but not including, 1db0724a01b558feb1ecae551782add1951a114a; 889b7da23abf92faf34491df95733bda63639e32 up to, but not including, 2405f64a95a7a094eb24cba9bcfaffd1ea264de4; 889b7da23abf92faf34491df95733bda63639e32 up to, but not including, 5093bbfc10ab6636b32728e35813cbd79feb063c; 5.15 | 6c52b12159049046483fdb0c411a0a1869c41a67, 1db0724a01b558feb1ecae551782add1951a114a, 2405f64a95a7a094eb24cba9bcfaffd1ea264de4, 5093bbfc10ab6636b32728e35813cbd79feb063c |
| Linux | Linux Kernel | 5.15 up to, but not including, 5.15.137; 5.16 up to, but not including, 6.1.59; 6.2 up to, but not including, 6.5.8; 6.6 | 5.15.137, 6.1.59, 6.5.8 |
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: mctp: perform route lookups under a RCU read-side lock Our current route lookups (mctp_route_lookup and mctp_route_lookup_null) traverse the net's route list without the RCU read lock held. This means the route lookup is subject to preemption, resulting in an potential grace period expiry, and so an eventual kfree() while we still have the route pointer. Add the proper read-side critical section locks around the route lookups, preventing premption and a possible parallel kfree. The remaining net->mctp.routes accesses are already under a rcu_read_lock, or protected by the RTNL for updates. Based on an analysis from Sili Luo <[email protected]>, where introducing a delay in the route lookup could cause a UAF on simultaneous sendmsg() and route deletion.
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
- 7.8 High severity
- 7.8 High severity
- 7.5 High severity
- 9.8 Critical severity
- 7.8 High severity
- 8.1 High severity
Spotted an error? Tell us.